Question and answer index

Each question has a direct link and a separate link that opens its explanation. Try the question before viewing the answer.

Case 01: The Missed Monday

• W1: Which ECG finding is classically associated with early hyperkalemia, while recognizing that the sequence is not reliable in an individual patient? · Answer and explanation
• W2: Which bedside finding points toward too much fluid (hypervolemia) rather than too little? · Answer and explanation
• W3: Which treatment actually removes potassium from the body, rather than stabilizing the heart or pushing potassium temporarily into cells? · Answer and explanation
• Q4: It is 18:43. The first potassium is 8.1 on a hemolyzed sample; the clean repeat was just drawn from the right arm and will not be back for about 25 minutes. The · Answer and explanation
• Q5: Mr. Hartman has taken lisinopril for 8 years with monthly pre-dialysis potassium values of 4.8–5.3 mEq/L. Which change in the last two weeks best explains a pot · Answer and explanation
• Q6: Nephrology asks you to state the indication for urgent dialysis. Which single finding, on its own, is an urgent dialysis indication for Mr. Hartman? · Answer and explanation
• Q7: He is 4 kg above dry weight with a JVP at the jaw, crackles halfway up both lungs, BP 178/96, and pulmonary edema on the film. He is essentially anuric — about · Answer and explanation
• Q8: It is 18:50. The QRS has narrowed to 122 ms after calcium. The repeat potassium is still pending (the hemolyzed value was 8.1); glucose 168; no meaningful urine · Answer and explanation
• Q9: If you were thinking "the potassium emergency is over — tonight's run can wait for his regular Friday session," and you then learn that his potassium has fallen · Answer and explanation
• Q10: On Thursday a hospitalist orders a peripheral IV for an antibiotic "just in case the shin flares." Mr. Hartman has a working left upper-arm fistula. Which instr · Answer and explanation

Case 02: The Thiazide and the Tumble

• Q1: Four patients each have a serum sodium of 124 mEq/L and a serum osmolality below 275 mOsm/kg. Match the pattern to the branch of the hyponatremia differential, · Answer and explanation
• Q2: A 66-year-old woman has serum sodium 122 mEq/L and serum osmolality 254 mOsm/kg. Which result best shows impaired excretion of electrolyte-free water and, when · Answer and explanation
• Q3: An 82-year-old, 50-kg nursing-home resident with advanced dementia has had a fever for three days. She is brought in lethargic. Serum sodium 158 mEq/L, urine os · Answer and explanation
• Q4: You are asked to classify her volume status before the urine studies return. Which bedside finding most strongly supports a hypovolemic branch over a euvolemic · Answer and explanation
• Q5: Her sodium is 118 mEq/L, glucose 108 mg/dL and measured serum osmolality 248 mOsm/kg. Which statement about the next step in the work-up is correct? · Answer and explanation
• Q6: Serum Na 118, serum osmolality 248, urine osmolality 420 mOsm/kg. She is orthostatic and 2.5 kg down. Chlorthalidone 25 mg was started three weeks ago; sertrali · Answer and explanation
• Q7: K 2.8, HCO₃⁻ 34, Cl 74, Mg 1.4; ECG with flattened T waves, U waves and a QTc of 468 ms; nauseated but not vomiting. Which statement about the pattern and its t · Answer and explanation
• Q8: Sodium 118 mEq/L with confusion, GCS 14, no seizure or cardiorespiratory distress. Which initial plan best addresses both cerebral symptoms and volume depletion · Answer and explanation
• Q9: If you were thinking hypovolemic (thiazide) hyponatremia , and you then learn that her urine sodium is 55 mEq/L , this hypothesis becomes: · Answer and explanation
• Q10: Ten hours in, her sodium has risen 7 mEq/L. What is the right move now? · Answer and explanation
• Q11: At discharge her seated BP is 144/86 and standing 138/82 without symptoms. Chlorthalidone has been stopped. Which plan is best? · Answer and explanation
• Q12: A different older patient eats mainly tea and toast, drinks 3 L of water daily, and has hypotonic hyponatremia with urine osmolality 85 mOsm/kg. What best expla · Answer and explanation

Case 03: The Sick Day That Wasn't Held

• W1: A 70-year-old ICU patient has Na 138 mEq/L, Cl 104 mEq/L, HCO₃ 18 mEq/L and albumin 2.0 g/dL. Your lab's normal anion gap is 8–12 mEq/L. How do you read the gap · Answer and explanation
• W2: A 55-year-old woman's creatinine rises from 0.8 mg/dL to 1.7 mg/dL over 36 hours. Urine output is 0.8 mL/kg/h. The lab prints eGFR 35. Her KDIGO AKI stage is: · Answer and explanation
• W3: stop while he is ill? · Answer and explanation
• Q4: If you were thinking diabetic ketoacidosis in a man on empagliflozin with three days of vomiting and fast, deep breathing, and you then learn that his glucose i · Answer and explanation
• Q5: Using the ABG and BMP above (pH 7.29, pCO₂ 30, HCO₃ 14, Na 134, Cl 86, albumin 4.0; your lab's normal gap is 8–12 and normal HCO₃ is 24), which statement best d · Answer and explanation
• Q6: Lactate is 1.6 mmol/L and the osmolal gap is 4 mOsm/kg. He takes empagliflozin and metformin. The resident says, "glucose is 206 — this isn't DKA." Which single · Answer and explanation
• Q7: Creatinine 1.9 mg/dL (baseline 1.0 three months ago), BUN 46, lab eGFR 40, specific gravity 1.028, hyaline casts only, 4 kg weight loss in a week and orthostasi · Answer and explanation
• Q8: It is hour 2. Potassium is 3.1 mEq/L, magnesium 1.8, β-hydroxybutyrate 5.8, glucose 188. He is on a cardiac monitor. The resident wants to start an insulin infu · Answer and explanation
• Q9: Hour 14: 5 L of 0.9 % saline in, chloride 104 (from 86), bicarbonate 15, anion gap 18, delta-delta 0.67, glucose 164, potassium 3.9, sodium 137. The insulin inf · Answer and explanation
• Q10: Day 3: Na 138, K 4.1, Cl 110, HCO₃ 17, anion gap 11, creatinine 1.1, β-hydroxybutyrate 0.3. Urine Na 60, K 30, Cl 115 (urine anion gap −25), urine pH 5.2. He re · Answer and explanation

Case 04: The Tired Teacher

• Q1: eGFR — the estimated glomerular filtration rate, the kidney's filtering rate calculated from creatinine, age and sex by the CKD-EPI 2021 equation — assumes the · Answer and explanation
• Q2: Four office blood pressures, four techniques. Which one is a reading you can make a treatment decision on? · Answer and explanation
• Q3: A first-morning urine dipstick reads "trace" protein; the UACR on the same sample is 180 mg/g. Which statement is correct? · Answer and explanation
• Q4: Ms. Jensen is on three antihypertensives and her office reading is 158/94 mmHg. What is the right response to that number today? · Answer and explanation
• Q5: Creatinine 1.72 mg/dL today (eGFR 34 mL/min/1.73 m² by CKD-EPI 2021), 1.6 mg/dL two years ago (eGFR 38), UACR 180 mg/g. Her KDIGO category, and what the 2024 va · Answer and explanation
• Q6: Her chart says "hypertensive kidney disease." She has never had a urinalysis with microscopy or a kidney ultrasound. What is the first-line work-up for the caus · Answer and explanation
• Q7: Hemoglobin 9.6 g/dL, MCV 78 fL, RDW 16.9 %, reticulocytes 0.9 %, eGFR 34; the iron studies and the stool guaiac card are still pending. What is the right anemia · Answer and explanation
• Q8: Sodium 139, chloride 108, bicarbonate 19 mEq/L, albumin 4.1 g/dL. How do you read this, and what is first-line? · Answer and explanation
• Q9: Calcium 9.1 mg/dL, phosphorus 4.6 mg/dL, intact PTH 118 pg/mL (reference 15–65), 25-OH vitamin D 17 ng/mL. Which plan belongs to primary care at G3b? · Answer and explanation
• Q10: If you were thinking "this is anemia of CKD — erythropoietin deficiency from an eGFR of 34 explains the hemoglobin of 9.6," and you then learn that her ferritin · Answer and explanation
• Q11: Home average 144/88 mmHg on lisinopril 40 mg, amlodipine 10 mg and hydrochlorothiazide 25 mg, adherence confirmed, eGFR 34, potassium 4.6 — and ibuprofen 600 mg · Answer and explanation
• Q12: Six weeks after the ibuprofen stopped and the chlorthalidone started, her repeat 7-day home average is 138/86 mmHg. Which statement is correct? · Answer and explanation
• Q13: A 62-year-old woman has stable CKD G3b, eGFR 34 mL/min/1.73 m², and LDL cholesterol 104 mg/dL. Her blood pressure is controlled, she does not have diabetes, and · Answer and explanation

Case 05: The Salt Substitute

• Q1: A 64-year-old man with type 2 diabetes has an eGFR below 60 on two tests more than three months apart (creatinine 1.8 mg/dL, eGFR 42 mL/min/1.73 m², fourteen mo · Answer and explanation
• Q2: The same man takes metformin 1,000 mg twice daily. At eGFR 39 mL/min/1.73 m², which statement is correct? · Answer and explanation
• Q3: Which drug class is NOT one of the four pillars of therapy for diabetic kidney disease? · Answer and explanation
• Q4: His picture is 12 years of type 2 diabetes, background retinopathy, UACR 900 mg/g with a bland sediment, symmetric kidneys and an eGFR falling about 3 mL/min pe · Answer and explanation
• Q5: He is on losartan 100 mg daily, metformin 1,000 mg twice daily and atorvastatin 40 mg. eGFR 39, UACR 900 mg/g, potassium 4.6 mEq/L, A1c 7.6 %. What is the best · Answer and explanation
• Q6: Creatinine has gone from 1.9 to 2.2 mg/dL (16 %) two weeks after starting empagliflozin on top of losartan. Taking the creatinine on its own, what does it mean · Answer and explanation
• Q7: Potassium 5.7 mEq/L (repeat 5.6), normal ECG, asymptomatic. He has used a potassium-chloride salt substitute for 12 days and naproxen 440 mg twice daily for 9 d · Answer and explanation
• Q8: His wife asks about "the new kidney pill" a neighbor takes — finerenone. With potassium 5.7 mEq/L today, eGFR in the 30s, BMI 31 and A1c 7.6 %, which statement · Answer and explanation
• Q9: One creatinine at Day 14 could not tell a dip from early injury. If you were thinking "the SGLT2 inhibitor has injured the kidney," and you then learn that at D · Answer and explanation
• Q10: Creatinine 2.9 mg/dL (from 2.0), potassium 5.9 mEq/L with a normal ECG, bicarbonate 20, orthostatic with a 3-kg weight loss, poor intake for three days, no urin · Answer and explanation
• Q11: One week after the ED visit he has eaten and drunk normally for 48 hours, orthostasis has resolved, creatinine is 2.1 mg/dL and potassium 4.8 mEq/L. His medicin · Answer and explanation

Case 06: The Breathless Farmer

• Q1: A 71-year-old man with heart failure arrives short of breath. Which single bedside finding most reliably tells you he is congested (volume overloaded)? · Answer and explanation
• Q2: Which list names the four pillars of guideline-directed medical therapy (GDMT) for heart failure with reduced ejection fraction (HFrEF)? · Answer and explanation
• Q3: A patient with heart failure on a loop diuretic and sacubitril-valsartan takes ibuprofen for back pain. By which mechanism does the ibuprofen lower his glomerul · Answer and explanation
• Q4: Creatinine 2.6 (baseline), BUN 52 (ratio 20:1), Na 127, 7 kg above dry weight, JVP 12 cm with hepatojugular reflux, S3, edema to the knees. Which statement is c · Answer and explanation
• Q5: He is alert, oriented, and has no headache, nausea or confusion. Serum osmolality 283 mOsm/kg, urine osmolality 380 mOsm/kg, urine sodium 22 mmol/L (before any · Answer and explanation
• Q6: Two hours after furosemide 40 mg IV (equal to his home oral dose), urine output is 180 mL and the spot urine sodium is 28 mmol/L. He remains 6 kg above dry weig · Answer and explanation
• Q7: At 05:30 on Day 2, before the pharmacist's call, the night resident saw creatinine 3.1 (up 19 % from 2.6), wrote "AKI — hold furosemide" and ordered a 1 L norma · Answer and explanation
• Q8: If you were thinking "the IV furosemide is causing prerenal (volume-depletion) injury," and you then learn that on Day 3 his weight is still 5 kg above his dry · Answer and explanation
• Q9: Day 3: still 5 kg above dry weight, JVP 12 cm, spot urine sodium 44 mmol/L two hours after furosemide 160 mg IV. Ibuprofen stopped yesterday. K⁺ 5.6, Mg 1.7, cr · Answer and explanation
• Q10: K⁺ 5.6 mEq/L, ECG unchanged (AF at 84, no peaked T waves, QRS 96 ms), baseline eGFR 26, creatinine 3.2 and expected to fall as he decongests. Spironolactone was · Answer and explanation
• Q11: Which response to the hospitalist is correct? · Answer and explanation

Case 07: The Grandmother's Urine Cup

• W1: Which urine dipstick pad depends on how long the urine sat in the bladder before it was voided? · Answer and explanation
• W2: A urine sediment shows white blood cell casts. Where did those white cells come from? · Answer and explanation
• W3: Which patient is most likely to develop hyponatremia after a thiazide diuretic is started? · Answer and explanation
• Q4: The facility asks you to treat her urinary tract infection. The bag-collected urinalysis shows 1+ leukocyte esterase, negative nitrite, 8 WBC/hpf, many squamous · Answer and explanation
• Q5: Her point-of-care sodium is 127 mEq/L (her value 3 months ago was 138). She started hydrochlorothiazide 4 weeks ago, has eaten little for 3 days, is 2.5 kg belo · Answer and explanation
• Q6: Her gabapentin was increased to 900 mg three times daily (2,700 mg/day) one week ago. Her creatinine was 1.4 mg/dL at baseline — eGFR 37 by CKD-EPI 2021, but a · Answer and explanation
• Q7: If you were thinking "a urinary tract infection explains her confusion," and you then learn that the straight-catheter specimen shows 4 WBC/hpf, no bacteria, ni · Answer and explanation
• Q8: The facility nurse calls at 13:20: "Her culture is back — it grew 50,000 colonies. Are you starting the antibiotic?" The catheter specimen shows 4 WBC/hpf, no b · Answer and explanation
• Q9: Her creatinine is 1.9 mg/dL against a baseline of 1.4 three months ago — a rise of 0.5 mg/dL, about a third above baseline, after three days of poor intake, wit · Answer and explanation
• Q10: Now suppose the straight-catheter specimen had instead shown 60 WBC/hpf, white-cell casts, nitrite positive and many uniform rod-shaped bacteria — and that she · Answer and explanation
• Q11: On hospital day 4 she is alert and oriented to her baseline, euvolemic, eating, sodium 137, potassium 4.1, creatinine 1.4 (eGFR 37). Blood pressure is 142/78 of · Answer and explanation

Case 08: The Sore Throat That Came Back

• W1: A 58-year-old man who has smoked a pack a day for 35 years reports two episodes of painless, bright-red urine with small clots at the end of the stream. No feve · Answer and explanation
• W2: A 9-year-old boy (height 136 cm, the 50th percentile for his age) has had three days of a non-blanching purple rash over his buttocks and legs, sore swollen kne · Answer and explanation
• W3: A 72-year-old man is three days out from septic shock that needed vasopressors. His creatinine has climbed from 1.0 to 2.6 mg/dL, urine specific gravity is 1.01 · Answer and explanation
• Q4: Cola-colored urine, dipstick 3+ blood and 2+ protein, BP 148/92, day two of pharyngitis, no dysuria, no flank pain. Which single step tells you whether this is · Answer and explanation
• Q5: Her urine turned dark on day two of the sore throat. Before any serology is back, which statement about timing is correct? · Answer and explanation
• Q6: Nephritic sediment on day two of a viral pharyngitis, UPCR 1.2 g/g, creatinine 1.0 with no prior value, C3 118 and C4 26 (both normal), rapid strep negative. Wh · Answer and explanation
• Q7: Creatinine 2.4 mg/dL today; her only prior value is 1.0 three weeks ago. The lab prints eGFR 29. The sediment is active (dysmorphic RBCs, acanthocytes, RBC cast · Answer and explanation
• Q8: You have named RPGN. It is 12:30 on a Monday in an outpatient clinic. Which set of orders is right for this afternoon? · Answer and explanation
• Q9: If you were thinking IgA nephropathy, and you then learn that today's C3 is 42 mg/dL and C4 is 8 mg/dL — both low — this hypothesis becomes: · Answer and explanation
• Q10: Admission potassium 5.6 mEq/L, bicarbonate 18, creatinine 2.4 and rising, ECG sinus rhythm with normal intervals and no peaked T waves, lungs clear, no edema be · Answer and explanation
• Q11: BP 158/98, UPCR 3.1 g/g, potassium 5.6, creatinine rising, urine hCG negative this morning, on a combined oral contraceptive. Nephrology plans a biopsy within 4 · Answer and explanation
• Q12: A 28-year-old develops hemoptysis, hypoxemia, bilateral alveolar opacities, red-cell casts and a creatinine rise from 1.0 to 3.4 mg/dL over five days. Anti-GBM · Answer and explanation

Case 09: The Diabetic Journey

• Q1: A 49-year-old woman with type 2 diabetes has a spot urine albumin-to-creatinine ratio (UACR) of 420 mg/g. Which statement places this result correctly? · Answer and explanation
• Q2: Four urine pictures from four patients. Which one is the nephrotic pattern? · Answer and explanation
• Q3: A patient with type 2 diabetes takes metformin 1,000 mg twice daily. Her eGFR has been stable at 38 mL/min/1.73 m² for six months. What is the correct metformin · Answer and explanation
• Q4: The UACR of 420 mg/g was collected the afternoon of a febrile illness. What is the best next step? · Answer and explanation
• Q5: Two weeks after lisinopril was raised to 20 mg and empagliflozin 10 mg was started, creatinine is 1.21 mg/dL (from 1.01) and potassium is 4.8 mEq/L. She feels w · Answer and explanation
• Q6: A 50-year-old woman with 16 years of type 2 diabetes, confirmed A3 albuminuria eighteen months ago, now presents with nephrotic syndrome (UPCR 7.8 g/g, albumin · Answer and explanation
• Q7: Furosemide 40 mg by mouth once daily for five days has produced a 0.3 kg weight loss. Albumin is 2.1 g/dL; she has gut-wall edema and ascites. What is the best · Answer and explanation
• Q8: Which action best reduces her risk from the complications of nephrotic syndrome? · Answer and explanation
• Q9: If you were thinking this is still diabetic kidney disease, and you then learn that a dilated eye exam this week shows no diabetic retinopathy, this hypothesis · Answer and explanation
• Q10: eGFR 21, potassium 5.5 mEq/L with a normal ECG, UACR 1,900 mg/g on lisinopril 40 mg and empagliflozin 10 mg. What is the best next step for her kidney-protectiv · Answer and explanation
• Q11: Her 4-variable Kidney Failure Risk Equation result is about 41 % at 2 years (about 81 % at 5 years). She is 52, works full time, and her sister has offered a ki · Answer and explanation
• Q12: In her first month on hemodialysis she arrives 4 kg above dry weight with 2+ edema, an interdialytic gain of 4 kg over the long weekend, 600 mL/day of residual · Answer and explanation

Case 10: Two Dark Urines

• W1: A 66-year-old woman admitted with pneumonia has a creatinine of 0.8 mg/dL on arrival, 1.3 mg/dL at 36 hours and 1.9 mg/dL on hospital day 3. Her urine output ha · Answer and explanation
• W2: Four patients on the same ward each have a creatinine that has doubled. A cast is a cylinder of protein that formed inside a tubule and then washed out — it tel · Answer and explanation
• W3: A 71-year-old man is on day 6 of gentamicin plus ampicillin for enterococcal endocarditis. His creatinine has gone from 1.1 to 1.9 mg/dL; he is still making 1.4 · Answer and explanation
• Q4: Patient A (Walter, 79): three days of diarrhea; BP 98/58 lying → 78/46 standing with heart rate 104 → 124; weight 74.5 kg, down 3.5 kg; dry mucosa, flat neck ve · Answer and explanation
• Q5: Walter's home list is lisinopril 20 mg daily, hydrochlorothiazide 25 mg every morning, naproxen 500 mg twice daily, metformin 1,000 mg twice daily, gabapentin 6 · Answer and explanation
• Q6: Jess's urine is tea-brown. Dipstick: blood 3+, protein 1+. Microscopy: 0–1 red cells per high-power field, pigmented granular casts, no red-cell casts. CK 48,00 · Answer and explanation
• Q7: Jess: potassium 6.2 mEq/L with peaked T waves in V2–V4; calcium 7.1 mg/dL (corrected 6.9) with no tingling, cramps or tetany; phosphorus 7.8 mg/dL; bicarbonate · Answer and explanation
• Q8: Jess weighs 66 kg, is tachycardic and mildly hypotensive, has vomited twice, and made 40 mL of dark urine in her first hour. Which fluid plan is right? · Answer and explanation
• Q9: If, from the history, orthostatics, weight loss, specific gravity 1.024 and hyaline casts, you were thinking "volume-responsive prerenal AKI" in Walter on day 1 · Answer and explanation
• Q10: Walter, day 3, after 2 L of lactated Ringer's boluses since 21:00 last night: BP 112/70, heart rate 88, JVP 7 cm, lungs clear, weight 77.0 kg (74.5 on arrival), · Answer and explanation
• Q11: Walter, day 3: creatinine 3.9 mg/dL and still rising; the BMP prints "eGFR 15." The admission orders carried over metformin 1,000 mg twice daily (held since day · Answer and explanation
• Q12: Walter, day 4: creatinine 4.4 mg/dL, K⁺ 5.8 mEq/L with a normal ECG, bicarbonate 17, urine output 25 mL/h, SpO₂ 95 % on room air, lungs clear, alert and eating · Answer and explanation

Case 11: The Stone in the Only Kidney

• W1: A 44-year-old man with no prior stones presents with 3 hours of sudden left flank pain radiating to the groin, vomiting, and microscopic hematuria. He is afebri · Answer and explanation
• W2: Four patients have a potassium result back. Which one gets IV calcium gluconate in the next five minutes? · Answer and explanation
• W3: An 81-year-old man with known benign prostatic hyperplasia (BPH — an enlarged prostate narrowing the bladder outlet) has passed no urine for 18 hours, has lower · Answer and explanation
• Q4: A 58-year-old man with a solitary right kidney, 14 hours of right flank colic, no urine for 12 hours, creatinine 5.1 mg/dL (baseline 1.1), and a bladder scan of · Answer and explanation
• Q5: Same patient, 09:55. K⁺ 7.0 mEq/L on the point-of-care cartridge (free-flowing sample; formal chemistry pending), QRS 150 ms with flattened P waves, total CO₂ 1 · Answer and explanation
• Q6: A 7-mm proximal ureteral stone in a 44-year-old with two kidneys usually leaves the creatinine near normal. Why did this man's creatinine go from 1.1 to 5.1 mg/ · Answer and explanation
• Q7: At 10:45, with the ECG settled, he is still writhing (pain 10/10), and the nurse asks for an analgesic order; the colic order set offers ketorolac. Creatinine 5 · Answer and explanation
• Q8: If you were thinking "an obstructed solitary kidney requiring urgent drainage, but without a superimposed infection," and you then learn he has a rectal tempera · Answer and explanation
• Q9: 11:45. Infected obstruction of a solitary kidney with sepsis physiology (T 38.6 °C, pulse 118, BP 102/58, lactate 3.1 mmol/L), K⁺ 5.6 and falling on the protoco · Answer and explanation
• Q10: Four hours after decompression of a solitary obstructed kidney: urine output 350 mL/h × 4 h, hemodynamically stable, no orthostasis, creatinine falling (5.1 → 4 · Answer and explanation
• Q11: At the 2-week post-discharge visit: creatinine 1.2 mg/dL, K⁺ 4.3, BP 148/88, stone analysis calcium oxalate monohydrate, first stone ever, solitary kidney. Whic · Answer and explanation

Case 12: The Mass in the Picture

• Q1: A 71-year-old woman with a serum albumin of 2.4 g/dL has a total calcium of 11.2 mg/dL. What is her albumin-corrected calcium? · Answer and explanation
• Q2: A patient has a confirmed, albumin-corrected calcium of 12.8 mg/dL. Which single test organizes the entire differential and should be sent first? · Answer and explanation
• Q3: A 67-year-old man with type 2 diabetes takes metformin 1,000 mg twice daily. His steady-state eGFR, which was 58 mL/min/1.73 m² last year, is now 27 mL/min/1.73 · Answer and explanation
• Q4: Corrected calcium 14.4 mg/dL, new confusion, creatinine 2.3 mg/dL (baseline 1.0), sodium 149 mEq/L, orthostatic. What is the right disposition from clinic? · Answer and explanation
• Q5: Creatinine 2.3 from 1.0, BUN 52, orthostatic and dry, ultrasound without hydronephrosis, a post-void residual of 40 mL, and an ED dipstick negative for blood an · Answer and explanation
• Q6: Corrected calcium 14.4 mg/dL with an intact PTH of 8 pg/mL. He takes a thiazide, chews 8–10 calcium-carbonate tablets a day, has lost 6 kg, and a solid vascular · Answer and explanation
• Q7: Hour 1 in the ED: the first liter of isotonic saline is in and the second is running at 250 mL/hour. He is still confused and his neck veins are still flat; cor · Answer and explanation
• Q8: Two months ago: painless gross hematuria for two days in a 67-year-old smoker, >100 RBC/hpf with normal (isomorphic) red-cell morphology, no protein, no casts, · Answer and explanation
• Q9: If you were thinking "his hypercalcemia is milk-alkali syndrome from the calcium carbonate, with the thiazide adding to it" — and you then learn that his PTHrP · Answer and explanation
• Q10: Day 2: creatinine 1.6 mg/dL and falling (baseline 1.0), so still in active AKI. The 5.1-cm solid vascular left renal mass needs characterization and staging. Wh · Answer and explanation
• Q11: Day 6, going home: creatinine 1.3 mg/dL (1.0 six months ago, 2.3 on arrival), metformin held, the thiazide stopped, the left mass booked with urology. The 2.0-c · Answer and explanation
• Q12: A 63-year-old patient has intermittent painless visible hematuria and 4 kg of unexplained weight loss. Renal-protocol CT shows a 3.2-cm solid enhancing renal ma · Answer and explanation

Case 13: The Transplant Tremor

• W1: A 70-year-old woman on furosemide and lisinopril takes naproxen for three days for knee pain, and her creatinine rises from 1.1 to 1.8 mg/dL. Which statement be · Answer and explanation
• W2: A 58-year-old man with type 2 diabetes and a urine albumin-to-creatinine ratio of 420 mg/g starts lisinopril 10 mg daily. At two weeks his creatinine is 1.2 mg/ · Answer and explanation
• W3: A 72-year-old man with CKD (eGFR 40 mL/min/1.73 m²) has taken colchicine 0.6 mg daily for a year to prevent gout flares. Urgent care prescribes clarithromycin f · Answer and explanation
• Q4: The lab calls while she is still in the room: creatinine 2.0 mg/dL (1.2 four weeks ago), potassium 5.8 mEq/L. She has a new tremor, a mild orthostatic drop, and · Answer and explanation
• Q5: Before the full panel is back you already have: a new fine tremor, evening headaches, creatinine 2.0 (from 1.2), potassium 5.8, and a fasting point-of-care gluc · Answer and explanation
• Q6: Her tacrolimus dose has not changed in fourteen months, and she has not missed or doubled a dose. If the level has risen, which drug on her list is the most lik · Answer and explanation
• Q7: Sodium 137, chloride 107, bicarbonate 19, potassium 5.8, albumin 4.0, urine pH 5.5. Which interpretation is correct? · Answer and explanation
• Q8: It is 2 p.m. The tacrolimus level will report at about 4:30 p.m., and the transplant nephrologist will call you once it does. Her ECG is normal. What is the rig · Answer and explanation
• Q9: If you were thinking tacrolimus toxicity — not the ibuprofen-and-diarrhea story alone — is driving her creatinine rise , and you then learn that the tacrolimus · Answer and explanation
• Q10: The transplant nephrologist reviews the level of 18.2 and recommends ending the unplanned diltiazem interaction. Which plan carries that decision out safely? · Answer and explanation
• Q11: Diltiazem is stopped. Her blood pressure will drift back toward 150/90 over the next week, and with one kidney that matters. Potassium today is 5.8. Which repla · Answer and explanation
• Q12: She calls your nurse line in February: twenty-four hours of vomiting, a temperature of 38.3 °C, and a cough. Urgent care last night prescribed clarithromycin fo · Answer and explanation

Case 14: The Young Hypertensive

• Q1: A 38-year-old man describes 20-minute spells of pounding headache, palpitations and drenching sweats three or four times a week. Between spells his BP is 128/82 · Answer and explanation
• Q2: At a walk-in clinic, a 45-year-old man's BP is recorded once as 158/96, taken as he walked in from the parking lot — talking, legs crossed, arm hanging at his s · Answer and explanation
• Q3: A 52-year-old man who ran out of his blood pressure pills two months ago has BP 224/128, blurred vision, retinal hemorrhages and exudates, and a creatinine of 2 · Answer and explanation
• Q4: Office average 162/98 with standardized technique; 7-day home average 154/96; no symptoms; age 26. What is the correct next move? · Answer and explanation
• Q5: You will draw labs today and plan a primary aldosteronism screen. Which change to her regimen today best lowers her BP without undermining that screen? · Answer and explanation
• Q6: Potassium 3.1, bicarbonate 32, blood pressure 162/98, urine potassium 42 and urine chloride 48 mEq/L, magnesium 1.9, no diuretic, no vomiting. Which interpretat · Answer and explanation
• Q7: You now suspect aldosterone excess. Which is the correct next step? · Answer and explanation
• Q8: If you were thinking primary aldosteronism (an adrenal making aldosterone on its own), and you then learn that her plasma renin activity — drawn six weeks after · Answer and explanation
• Q9: A 26-year-old non-smoker with a normal aorta, a beaded mid-to-distal right renal artery, equal-sized kidneys, a high renin and a creatinine of 0.7. Which pairin · Answer and explanation
• Q10: Eight weeks pregnant, BP 138/88 on lisinopril 20 mg. What do you do today? · Answer and explanation
• Q11: BP 168/112 confirmed at 15 minutes, headache, RUQ pain, platelets 92,000, AST 190, UPCR 0.9 g/g. What is the correct immediate management? · Answer and explanation
• Q12: Postpartum day 5, BP 184/118 confirmed, headache, otherwise normal exam, normal platelets, liver enzymes, creatinine and head CT. Which assessment and first act · Answer and explanation

Case 15: The Family Discovery

• W1: A 44-year-old woman who smokes has 2+ blood on two dipsticks a month apart. Microscopy: 12 RBC/hpf, uniform round cells (isomorphic), no casts. Protein negative · Answer and explanation
• W2: A 29-year-old man has sudden severe left flank pain radiating to the groin, one episode of vomiting, dipstick blood 3+, no fever and a normal creatinine. Which · Answer and explanation
• W3: A 72-year-old woman with stable CKD (eGFR 26 mL/min/1.73 m², not on dialysis) has suspected bowel ischemia, and the surgeon wants a CT with IV contrast tonight. · Answer and explanation
• Q4: Ultrasound shows two enlarged polycystic kidneys and no hydronephrosis. Mr. K. still has colicky right flank pain and gross hematuria, and he is afebrile. What · Answer and explanation
• Q5: His father died of a ruptured intracranial aneurysm. Mr. K. has no headache and a normal neurological exam. What does this part of the history change for him? · Answer and explanation
• Q6: BP 146/92 and 144/90 today, "a little high" two years ago, three doses of ibuprofen yesterday, two polycystic kidneys. What is the right plan for his blood pres · Answer and explanation
• Q7: No stone, no hydronephrosis, a dense 4.1-cm cyst, hemoglobin 15.1, afebrile, pain 4/10 on acetaminophen. What is the best plan for the hematuria? · Answer and explanation
• Q8: A healthy 19-year-old with no symptoms and a normal blood pressure, whose father died of ADPKD and whose brother has just been diagnosed, asks you to order a re · Answer and explanation
• Q9: A 38-year-old woman with an affected father and brother has a single 2.0-cm thin-walled anechoic cyst in the left kidney on an ultrasound done for gallstones. C · Answer and explanation
• Q10: It is 23:00 in the emergency department: a 41-year-old man with ADPKD, 39.0 °C, rigors, pulse 108, a tender right kidney, WBC 15.8, no stone or hydronephrosis o · Answer and explanation
• Q11: If you were thinking infected cyst , and you then learn that the urine culture drawn before the first antibiotic dose is negative at 48 hours while the fever pe · Answer and explanation
• Q12: A 49-year-old man with ADPKD, eGFR 22 and falling about 6 mL/min a year, no uremic symptoms, potassium 4.9. His 34-year-old brother — four negative ultrasounds, · Answer and explanation

Case 16: The Late Referral

• W1: Four patients with advanced CKD call the nephrology office on the same afternoon. Which one needs dialysis started urgently? · Answer and explanation
• W2: A kidney failure risk calculator (the KFRE — inputs age, sex, eGFR and urine albumin-to-creatinine ratio) reports a 66-year-old woman's "2-year risk: 35%." What · Answer and explanation
• Q3: Two years ago Mrs. Brecht's primary-care labs showed a creatinine of 1.9 (eGFR 29, down from 36 a year earlier) and a first UACR of 520 mg/g. She was 64 and fel · Answer and explanation
• Q4: If you were thinking "she needs dialysis started now — her eGFR is 17 and she is nauseated," and you then learn that four weeks into oral sodium bicarbonate her · Answer and explanation
• Q5: Joan is 66 and independent, recovering from the toe infection, with no heart failure or cancer. Her eGFR is 17 and falls 6–7 points a year; her KFRE is 35% at 2 · Answer and explanation
• Q6: Joan is right-handed. The PICC ran through a vein in her left upper arm, and a firm cord still marks it. If a transplant does not come first, she will need hemo · Answer and explanation
• Q7: The printout says: "Kidney diet: protein 0.3 g/kg a day, no fruits or vegetables, no dairy." Joan weighs 75 kg and lost 3 kg with the infection. At the four-wee · Answer and explanation
• Q8: Two women from one household, both with advanced CKD. Joan: 66, independent, eGFR 17, transplant evaluation under way. Agnes: 88, moderate dementia, heart failu · Answer and explanation

Case 17: The Octogenarian's Numbers

• W1: An 88-year-old man who weighs 58 kg has a creatinine of 2.4 mg/dL at a routine visit; the laboratory reports an eGFR of 25 (CKD-EPI 2021). Which statement about · Answer and explanation
• W2: A patient with an eGFR of 25 asks which over-the-counter laxative is safest for long-term use. What do you recommend? · Answer and explanation
• Q3: Walter takes apixaban 5 mg twice daily for atrial fibrillation. He is 88, weighs 58 kg, and his creatinine four months ago was 2.4 mg/dL (eGFR 25; Cockcroft–Gau · Answer and explanation
• Q4: Walter's pressure is 126/68 seated and 104/60 standing at one minute, with lightheadedness, on amlodipine 10 mg daily; two days ago he nearly fainted. He is 88, · Answer and explanation
• Q5: At 11:20: potassium 6.1, magnesium 7.4, creatinine 2.9 (2.4 four months ago), bicarbonate 19, glucose 60 before the juice. The ECG shows atrial fibrillation at · Answer and explanation
• Q6: In the emergency department Walter's potassium is 6.0 with peaked T waves, his magnesium 7.3 with absent reflexes, pulse 46, BP 108/62 lying down, glucose 96 af · Answer and explanation
• Q7: If you were thinking "progressive kidney failure requires starting dialysis during this admission," and you then learn that his six clinic values over the past · Answer and explanation
• Q8: You ask yourself the surprise question — "Would I be surprised if Walter died in the next 12 months?" — and the honest answer is no: he is 88, frail, and has ju · Answer and explanation

Case 18: The Lithium Thirst

• W1: An 81-year-old man has had three days of fever and poor intake. Which single bedside finding is the most reliable evidence that he is volume depleted? · Answer and explanation
• W2: A 66-year-old woman started hydrochlorothiazide 25 mg daily for hypertension six weeks ago. Which set of laboratory changes is the thiazide's signature, and whe · Answer and explanation
• Q3: Mrs. Abernathy is 72 and 60 kg, with a blood pressure of 94/56 lying, a heart rate of 112, 3.5 kg below her clinic weight, sodium 157, creatinine 2.0 (baseline · Answer and explanation
• Q4: If you were thinking hypernatremia explained solely by lack of water access, with normal urinary concentrating ability , and you then learn that her urine osmol · Answer and explanation
• Q5: After stabilization, sodium 149; urine osmolality 160 mOsm/kg before desmopressin 2 mcg IV and 172 two hours after; 30 years of lithium; thirst and night urinat · Answer and explanation
• Q6: Corrected calcium 12.2 mg/dL (10.3 eight months ago), intact PTH 84 pg/mL, creatinine 2.0 and still moving, hydrochlorothiazide for six weeks, lithium for 30 ye · Answer and explanation
• Q7: After treatment for lithium-associated decreased consciousness, she is alert, with creatinine 1.6 (baseline 1.0), lithium 0.6, sodium 147 and a painful knee. Wh · Answer and explanation
• Q8: After recovery of this acute water-balance problem, serial measurements over several years show a sustained fall in eGFR in a patient receiving long-term lithiu · Answer and explanation

Case 19: The Post-Op Problem

• W1: After a laparoscopic hysterectomy, a 50-kg woman with pain and nausea will need IV fluid for a day. Which order carries the highest risk of lowering her sodium? · Answer and explanation
• W2: Two women each have a serum sodium of 121 mEq/L. In one it fell over 36 hours after surgery; in the other it drifted down over three months on a new medicine. W · Answer and explanation
• Q3: Post-operative day 2: sodium 121, serum osmolality 250, urine osmolality 540, urine sodium 70, BUN 8, uric acid 2.6; no orthostatic change, moist mucosa, normal · Answer and explanation
• Q4: It is 21:45, the urine results are in, and she is symptomatic with a sodium of 121 and a hemolyzed potassium of 6.4 with a normal ECG. Which set of orders is ri · Answer and explanation
• Q5: If you were thinking SIADH , and you then learn that her sodium fell from 121 to 119 overnight after a liter of 0.9% saline , this hypothesis becomes: · Answer and explanation
• Q6: Ms. Novak (60 kg before surgery), sodium 119; a generalized seizure just stopped with lorazepam, and she remains obtunded; glucose normal. What is the sodium tr · Answer and explanation
• Q7: At 14:00 her sodium is 126, up 7 from 119 at 07:05. Urine output is 260 mL/h with a urine osmolality of 110. What now? · Answer and explanation

Case 20: The Stone Former with Low Potassium

• W1: A 41-year-old man has sudden, severe left flank pain radiating to the groin. He cannot lie still, has no fever, and his urine shows blood. Which test best confi · Answer and explanation
• W2: A 50-year-old man has had five days of watery diarrhea: sodium 136, chloride 112, bicarbonate 16 (anion gap 8). A spot urine shows sodium 30, potassium 25 and c · Answer and explanation
• Q3: Sodium 139, chloride 114, bicarbonate 17, potassium 3.0; arterial pH 7.33 with a pCO₂ of 33. What is the acid–base disorder, and what should be added to her tri · Answer and explanation
• Q4: If you were thinking diarrhea-related non-gap acidosis , and you then learn that her urine anion gap is +22 mEq/L (on the triage urine, pH 6.5, taken while her · Answer and explanation
• Q5: Off diarrhea for two weeks: bicarbonate 18, potassium 3.1, urine pH 6.6, urine anion gap +22 at the first visit, calcium phosphate stones with nephrocalcinosis, · Answer and explanation
• Q6: Distal RTA from Sjögren syndrome, 58 kg: potassium 3.1, bicarbonate 18; 24-hour urine volume 1.4 L, calcium 290 mg/day, citrate 90 mg/day, pH 6.8. Which plan is · Answer and explanation

Case 21: The Executive Physical

• W1: Two protocol office readings are 138/92 and 134/90 mmHg. Using the 2025 AHA/ACC office categories, how is this blood pressure classified? · Answer and explanation
• W2: A man with hypertension and obesity plans to lose 5 kg. Using the guideline estimate of roughly 1 mmHg systolic reduction per kilogram lost, what is a reasonabl · Answer and explanation
• Q3: Mr. Hollister, 52, has two protocol office readings averaging 144/91 mmHg. He takes pseudoephedrine most mornings and naproxen on golf days, snores with witness · Answer and explanation
• Q4: Mr. Hollister's home average is 141/88 mmHg, two weeks off pseudoephedrine and naproxen. On single samples his eGFR is 58 and his UACR 48 mg/g; the potassium is · Answer and explanation
• Q5: If you were thinking "primary (essential) hypertension — his weight, salt, alcohol, decongestant and probable sleep apnea explain it," and you then learn that t · Answer and explanation
• Q6: Eight weeks after the physical, endocrinology adds spironolactone 25 mg daily. His list is now lisinopril 20 mg, amlodipine 5 mg, spironolactone 25 mg, and the · Answer and explanation
• Q7: At week 15 his electronic chart still carries "CKD stage 3a," auto-entered from visit 1. His eGFR has been 66 and 63 since he stopped naproxen; his UACR was 48 · Answer and explanation
• Q8: At follow-up, obesity, hypertension, impaired glucose regulation and persistent albuminuria remain on his problem list. What does the cardiovascular–kidney–meta · Answer and explanation

Case 22: The Medication Minefield

• W1: The adult gabapentin label provides a renal-dose table in creatinine clearance. In a patient with stable kidney function, which estimate does that label describ · Answer and explanation
• W2: Which three-drug combination is the "triple whammy" for acute kidney injury? · Answer and explanation
• Q3: Mr. Brandt is 74, weighs 80 kg, and his creatinine is 2.7 mg/dL (eGFR 24 by CKD-EPI 2021). He takes rivaroxaban 20 mg daily for atrial fibrillation. What is the · Answer and explanation
• Q4: Same visit. Mr. Brandt takes metformin 1,000 mg twice daily, gabapentin 900 mg three times daily and naproxen most days, alongside losartan and furosemide. He i · Answer and explanation
• Q5: Mr. Brandt (eGFR 24, on losartan and furosemide) is booked for a colonoscopy with a sodium phosphate tablet prep, and for a contrast MRI to characterize a 2-cm · Answer and explanation
• Q6: If you were thinking "his magnesium of 1.2 is dietary — a widower living on tea and toast," and you then learn that 10 days after omeprazole was switched to fam · Answer and explanation
• Q7: Mr. Brandt has CKD G4, atrial fibrillation and a written plan for a vomiting illness with poor fluid intake. Which instruction best combines temporary holds wit · Answer and explanation
• Q8: A patient with advanced CKD takes magnesium-containing laxative repeatedly, then develops lethargy, reduced tendon reflexes and bradycardia. Magnesium is marked · Answer and explanation

Case 23: The Resistant Heart Failure

• W1: Which set of findings defines nephrotic syndrome? · Answer and explanation
• W2: Which drug–kidney lesion pairing is correct? · Answer and explanation
• Q3: Mr. Kessler, 66, has gained 10 kg, has periorbital and thigh-high pitting edema, a jugular venous pressure of 6 cm, clear lungs and no S3, and a "diuretic-resis · Answer and explanation
• Q4: If you were thinking "diuretic-resistant heart failure," and you then learn that his BNP is 42 pg/mL — drawn this morning, while he is 10 kg above his usual wei · Answer and explanation
• Q5: Mr. Kessler's sodium is 131 mEq/L with a measured serum osmolality of 274 and urine osmolality of 420; he has thigh-high edema, albumin 1.9, a UPCR of 9.1 g/g, · Answer and explanation
• Q6: Day 7, nephrology clinic. The screen is back: A1c 5.5%; HIV, hepatitis B surface antigen, hepatitis C antibody, RPR and ANA negative; C3 and C4 normal; serum pr · Answer and explanation
• Q7: Day 18. Mr. Kessler, with membranous nephropathy and albumin 1.8, has new left flank pain and gross hematuria; creatinine 2.1 from 1.3 four days ago; stable wei · Answer and explanation

Case 24: The Two Swollen Cousins

• W1: A 4-year-old boy at the 50th height percentile has a BP of 112/70, repeated by auscultation with a correctly sized cuff. The AAP 2017 table for his age and heig · Answer and explanation
• W2: Which threshold defines nephrotic-range proteinuria in a 4-year-old child? · Answer and explanation
• Q3: Jalen, 4, has abrupt edema, UPCR 9.6 g/g, albumin 1.7 g/dL, cholesterol 368, BP below his 90th percentile, a normal creatinine (Schwartz eGFR 125), normal C3 an · Answer and explanation
• Q4: On day 9 of prednisone Jalen is still swollen, with ascites. Tonight his temperature is 39.2 °C, he cries when lifted because his whole belly hurts, and he has · Answer and explanation
• Q5: Marcus, 36, weighs 128 kg (BMI 38) and has edema to the thighs, UPCR 11.2 g/g, albumin 2.2 g/dL, cholesterol 312, BP 150/94, a creatinine of 1.9 with no earlier · Answer and explanation
• Q6: If you were thinking "primary FSGS," as the urgent-care note did, and you then learn that Marcus's HIV test is reactive with a viral load of 480,000 copies/mL a · Answer and explanation
• Q7: Marcus has nephrotic syndrome with a viral load of 480,000 copies/mL, a CD4 count of 190, large echogenic kidneys, a creatinine of 1.9, potassium 4.9 and BP 150 · Answer and explanation

Case 25: The Puffy Second-Grader

• W1: A 6-year-old girl has cola-colored urine and puffy eyes four weeks after impetigo on her legs. Which test is most likely to show that she had a recent streptoco · Answer and explanation
• W2: A 5-year-old girl has had four days of a raised, non-blanching purple rash over her buttocks and the backs of her legs, swollen painful ankles and cramping bell · Answer and explanation
• Q3: Mateo, 7, has puffy eyes, cola-colored urine, less urine than usual, 1.9 kg of new weight, BP 128/84 (repeat 126/84) against a 95th percentile of 112/73 and a s · Answer and explanation
• Q4: Mateo's creatinine is 0.9 mg/dL today; it was 0.4 mg/dL ten months ago, and the lab flags nothing because it printed its adult range of 0.6–1.2. Which statement · Answer and explanation
• Q5: On the ward: BP 126/84, edema, less urine, creatinine 0.9 (2.25 times baseline), potassium 5.3 with a normal ECG, C3 38 with a normal C4, anti-DNase B 1,120, RB · Answer and explanation
• Q6: Before discharge, his parents ask what should bring Mateo back early. Which of these developments over the coming weeks needs same-day evaluation and a call to · Answer and explanation
• Q7: If you were thinking "uncomplicated post-streptococcal GN," and you then learn that at ten weeks — with his BP and creatinine back to normal — his C3 is still l · Answer and explanation

Case 26: The Sports Physical

• W1: A 16-year-old swimmer, 188 cm tall (above the 95th height percentile), has a BP of 134/78 on three visits with a correctly sized cuff. How is his BP classified? · Answer and explanation
• W2: Which urine sample is most likely to give a falsely positive dipstick protein? · Answer and explanation
• Q3: Ethan, 16, came straight from two hours of basketball. His dipstick shows specific gravity 1.030, protein 2+ and trace blood; he feels well and has no edema. Wh · Answer and explanation
• Q4: Ethan's first-morning urine has no protein (UPCR 0.08 g/g) but his 4 p.m. sample does (UPCR 0.46 g/g); the morning microscopy shows 8–10 RBC/hpf, most of them d · Answer and explanation
• Q5: If you were thinking "a benign orthostatic finding — reassure him and close the chart," and you then learn that both new specimens again show dysmorphic red cel · Answer and explanation
• Q6: Walt, 62, has had two episodes of painless gross hematuria with clots. He has 40 pack-years of smoking, takes apixaban, and was treated for a "UTI" whose cultur · Answer and explanation
• Q7: A father and daughter have slowly progressive CKD, little protein or blood in the urine, and a family history of early gout. Which inherited pattern should prom · Answer and explanation

Case 27: The Day-Six Creatinine

• W1: A 39-year-old man is on day 9 of cephalexin for leg cellulitis. His creatinine has risen from 0.9 to 1.8 mg/dL; he passes normal volumes of urine and has no fev · Answer and explanation
• W2: A 66-year-old woman with type 2 diabetes and stable CKD G3a (eGFR 52 mL/min/1.73 m² on three checks over a year) takes metformin 500 mg twice daily and is booke · Answer and explanation
• Q3: Dale, 61, day 6 of vancomycin plus piperacillin-tazobactam, after three doses of gentamicin and two days of ketorolac: creatinine 1.0 → 1.3 → 2.3 mg/dL; urine 1 · Answer and explanation
• Q4: If you were thinking "vancomycin tubular injury (ATN) is the sole explanation for Dale's AKI," and you then learn that on day 8 he has a new rash, a temperature · Answer and explanation
• Q5: Dale, day 8: stage 2 AKI (probable tubular injury with suspected drug-induced AIN), creatinine 2.8 mg/dL and rising, euvolemic, urine 1.7 L/day, metformin still · Answer and explanation
• Q6: Dale, day 9: creatinine 3.1 mg/dL and rising (1.0 → 2.3 → 2.8 → 3.1); printed eGFR 22; admission eGFR 86; Cockcroft–Gault about 29 mL/min. Enoxaparin 40 mg dail · Answer and explanation
• Q7: Dale, day 15: creatinine 1.7 mg/dL and falling (baseline 1.0; peak 3.2 on day 10); probable nephrotoxic tubular injury plus suspected piperacillin-tazobactam AI · Answer and explanation
• Q8: Weeks later a culture suggests an infection for which gentamicin may be needed. Dale has a prior nephrotoxic AKI. Which prescribing step best limits avoidable h · Answer and explanation

Case 28: The Lymphoma Admission

• W1: A 52-year-old woman with acute myeloid leukemia and a white count of 140,000/µL is 20 hours into induction chemotherapy. Which set of results is the tumor lysis · Answer and explanation
• W2: A student summarizes the hyperkalemia treatments for her team. Which summary is correct? · Answer and explanation
• Q3: Russ, 58, before his first R-CHOP: bulky DLBCL (14-cm mass), LDH 1,860 U/L (about 6.6 times the upper limit), uric acid 9.1 mg/dL, phosphorus 4.7 mg/dL, creatin · Answer and explanation
• Q4: Russ, 04:15: potassium 6.4 mEq/L with peaked T waves in V2–V5 and a QTc of 500 ms; calcium 6.8 mg/dL (corrected 6.9, ionized 0.88 mmol/L) with perioral tingling · Answer and explanation
• Q5: Russ, 04:40: calcium given, T waves narrower, spasm gone; insulin, dextrose and albuterol given. Still dry, urine 15 mL/h, BP 106/62, lungs clear; uric acid 14. · Answer and explanation
• Q6: If you were thinking "tumor lysis syndrome" from Russ's chemistry, and you then learn that his 09:00 urine holds sheaves of needle-shaped crystals, this hypothe · Answer and explanation
• Q8: Russ has worsening AKI after two acyclovir doses infused over 30 minutes while dehydrated. The fresh urine contains needle-shaped crystals. What is the safest n · Answer and explanation
• Q7: Russ, hour 30: potassium back to 6.6 mEq/L with peaked T waves despite a second insulin dose and a binder; phosphorus 10.2 mg/dL with recurrent carpal spasm; ur · Answer and explanation

Case 29: The Cirrhotic's Creatinine

• W1: In decompensated cirrhosis three findings travel together — a urine sodium below 10 mEq/L, a falling serum sodium and a creeping creatinine — while the patient · Answer and explanation
• W2: FENa — the fraction of filtered sodium that ends up in the urine — is context dependent. In which patient is it most useful to help distinguish volume-responsiv · Answer and explanation
• Q3: Dennis: creatinine 2.2 mg/dL (0.9 three weeks ago), BP 96/58 lying and 80/50 standing, weight down 3 kg, temperature 37.8 °C, mild diffuse abdominal tenderness, · Answer and explanation
• Q4: Day 1 orders for Dennis: alert, no asterixis; sodium 124 mEq/L; potassium 5.8 mEq/L with a normal ECG; ascitic neutrophils 420/µL, Gram stain negative; temperat · Answer and explanation
• Q5: If, on admission, you were thinking "volume-responsive prerenal AKI" — a man dried out by two diuretics, poor eating and an NSAID — and you then learn that 48 h · Answer and explanation
• Q6: Day 3: Dennis meets the HRS-AKI criteria (creatinine 0.9 → 2.7 mg/dL; no improvement in the 24 hours after his volume was restored, with diuretics and NSAID sto · Answer and explanation

Case 30: The Prostate Problem

• W1: A 76-year-old man with BPH, on no prostate medicine, urinates every hour, can barely hold it and gets up five times a night. Before anyone treats this as an ove · Answer and explanation
• W2: A 68-year-old woman, unwell for two weeks: sodium 138, chloride 114, bicarbonate 16 mEq/L, albumin 4.0 g/dL; urine sodium 30, potassium 25, chloride 75 mEq/L. W · Answer and explanation
• Q3: Leonard, 79: confused, three days of overflow dribbling, a tender bladder palpable to the umbilicus, bladder scan about 900 mL, creatinine 3.6 mg/dL (1.2 eight · Answer and explanation
• Q4: Leonard at 14:10: potassium 5.6 mEq/L with a normal ECG; chloride 109, bicarbonate 18, anion gap 10; arterial pH 7.33 with pCO₂ 35; urine anion gap +20; the cat · Answer and explanation
• Q5: Leonard at 19:00: urine output 420, 360, 330, 310 and 300 mL in the five hours since the 950-mL residual drained; BP 138/78, heart rate 88; still drowsy and onl · Answer and explanation
• Q6: If, on arrival — confused, with cloudy catheter urine, pyuria and a positive nitrite — you were thinking "urosepsis," and you then learn that the catheter urine · Answer and explanation
• Q7: Day 3: Leonard is alert; creatinine 1.7 mg/dL and falling; output 110 mL/h; drinking well. BP 146/82 lying and 130/76 after 3 minutes standing, without symptoms · Answer and explanation

Session 5 readiness quiz

• Q1: A patient with membranous nephropathy and serum albumin 1.8 g/dL develops flank pain, gross hematuria and a creatinine rise from 1.3 to 2.1 mg/dL over four days · Answer and explanation
• Q2: A patient with cirrhosis and ascites has persistent AKI after appropriate correction of a documented volume deficit. Infection, obstruction and nephrotoxic expo · Answer and explanation
• Q3: An acutely unwell adult has the results below. Creatinine was 1.0 mg/dL five days earlier. Which first interpretation uses the systematic BMP read correctly? · Answer and explanation