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Question and answer links
- 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. · Answer
- W2: Which threshold defines nephrotic-range proteinuria in a 4-year-old child? · Answer
- 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 crea · Answer
- Q4: On day 9 of prednisone Jalen is still swollen, with ascites. Tonight his temperature is 39.2 °C, he cries when lifted be · Answer
- 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 · Answer
- Q6: If you were thinking "primary FSGS," as the urgent-care note did, and you then learn that Marcus's HIV test is reactive · Answer
- Q7: Marcus has nephrotic syndrome with a viral load of 480,000 copies/mL, a CD4 count of 190, large echogenic kidneys, a cre · Answer
Session S3 · 2026-10-28 · supplementary · 20 min Anchor: Nephrotic syndrome at 4 and at 36 in one family · Integrates: pediatric BP by percentile, the nephrotic threshold in a child, nephrotic complications (infection, thrombosis), the adult secondary-cause screen, the drug → lesion table, who is biopsied and who is not One-line hook: Two cousins, a 4-year-old and a 36-year-old, swell up in the same week with the same 4+ protein on the dipstick. Same family, same word — nephrotic — and two very different first moves. Self-study after Session 3; commit to each answer before you open it.
Learning Objectives
Answers for this section: W1 · W2 · Q3 · Q4 · Q5 · Q6 · Q7
- Classify a child's blood pressure from the age-sex-height percentile table, and state the nephrotic-range protein threshold for a child and for an adult.
- Recognize typical childhood minimal change disease and explain why it is treated with a corticosteroid without a biopsy, while an adult generally needs a cause-directed work-up and a nephrology decision about biopsy.
- Anticipate the infection and clotting complications of nephrotic syndrome, and act the same day on fever with abdominal pain in a nephrotic child.
- Separate primary from secondary FSGS and send HIV, hepatitis B and C serologies in every new adult nephrotic work-up (pairing each virus with its lesion: discussed, not tested).
- Stop an NSAID in new nephrotic syndrome and explain why, in a typical child, it is a confounder rather than the cause (the drug → lesion table: discussed, not tested).
Warm-Up (individual commit before the case)
Answers for this section: W1 · W2
W1A 4-year-old's blood pressure
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 height gives a 90th percentile of 105/62, a 95th of 108/66 and a 95th + 12 mmHg line of 120/78. How is this reading classified?
Normal, because it sits below the adult elevated-BP line of 120/80
Elevated BP, because both numbers lie between his 90th and 95th percentile
Stage 1 hypertension range: at or above the 95th, below the 95th + 12 line
Stage 2 hypertension range, because he is above the 95th percentile for age
Show answer and explanation · Link to this question
Correct answer: C
Learning point: Under 13, blood pressure is read against age, sex and height, because taller children normally run higher pressures. Both of his numbers sit at or above the 95th percentile (112 ≥ 108, 70 ≥ 66) and below the 95th + 12 line (120/78): the stage 1 range, which becomes a diagnosis only after elevated readings on three occasions. It matters in this case because a normal blood pressure is one of the features that makes childhood nephrotic syndrome typical. Why not the others: A applies an adult cut-point to a 4-year-old; B misreads the table — both values are past the 95th, not between the 90th and 95th; D needs a reading at or above 120/78. Course reading: Evidence for this case
W2Nephrotic range in a small body
Which threshold defines nephrotic-range proteinuria in a 4-year-old child?
A spot UPCR at least 2 g/g, or at least 1,000 mg/m²/day on a timed urine
More than 3.5 g of protein in 24 hours, the same line used in adults
A urine albumin-to-creatinine ratio above 300 mg/g, the KDIGO A3 category
A dipstick protein of 1+ or more on two separate random urine specimens
Show answer and explanation · Link to this question
Correct answer: A
Learning point: A child loses far less protein in absolute terms than an adult, so the pediatric line is scaled to body size: at least 1,000 mg/m²/day on a timed collection, or a spot UPCR of at least 2 g/g. For a 4-year-old (about 0.75 m²) that is roughly 0.75 g a day, so he can be profoundly nephrotic — anasarca, a very low albumin — well below the adult 3.5 g. Low albumin, edema and high cholesterol complete the syndrome at any age. Why not the others: B is the adult definition; C is the albuminuria category A3, not the nephrotic line; D marks protein worth quantifying, not the nephrotic range. Course reading: Evidence for this case
Part 1 — Presentation
Answers for this section: Q3 · Q4
A Monday in October, a pediatric clinic. Jalen is 4. Five days ago his eyelids were puffy when he woke up, and his mother blamed allergies. By Saturday his socks left deep marks and his belly looked round; on Sunday night his scrotum was swollen, which brought them in. He is tired and picky with food. No one has seen blood in his urine. No rash, no joint pain, no fever this week.
Twelve days ago he had a cold with ear pain. His mother gave children's ibuprofen three or four times a day for seven days; no antibiotic was prescribed. His vaccines are up to date for age, and no one in the family is known to have kidney disease. You will meet his cousin Marcus in Part 2.
Vitals: T 36.8 °C · HR 104 · RR 24 · BP 98/56 (right arm, child cuff, auscultation) · SpO₂ 99% on room air · weight 19.4 kg (17.8 kg at his well visit 3 months ago) · height 106 cm (50th percentile). At his age and height the 90th percentile is 105/62.
Exam: Puffy eyelids; pitting edema to both knees; scrotal edema; a soft, distended abdomen with shifting dullness and no tenderness. Lungs clear, heart regular, no gallop. No purpura. Alert and cranky.
| Drug | Dose | Route | Frequency | Indication |
|---|---|---|---|---|
| Ibuprofen suspension (100 mg/5 mL) | 180 mg (9 mL) | PO | every 6–8 h as needed — given 3–4 times daily for 7 days; last dose 5 days ago | Ear pain with a cold |
| Cetirizine | 2.5 mg | PO | daily — started 4 days ago | Puffy eyes, presumed allergy |
Same-day results
| Test | Result | Reference range |
|---|---|---|
| Urine dipstick | protein 4+, blood negative, specific gravity 1.026 | protein and blood negative; SG 1.005–1.030 |
| Urine microscopy | 0–1 RBC/hpf; oval fat bodies; a few hyaline casts; no RBC casts | 0–2 RBC/hpf; no casts |
| Urine protein-to-creatinine ratio | 9.6 g/g | <0.2 g/g |
| Serum albumin | 1.7 g/dL | 3.5–5.0 g/dL |
| Total cholesterol | 368 mg/dL | <170 mg/dL |
| Sodium / potassium | 135 / 4.6 mEq/L | 135–145 / 3.5–5.0 mEq/L |
| Chloride / bicarbonate | 106 / 23 mEq/L | 98–107 / 22–29 mEq/L |
| Anion gap, Na − (Cl + HCO₃) | 6; albumin-corrected 12 (6 + 2.5 × 2.3) | 8–12 mEq/L |
| BUN | 10 mg/dL | 5–18 mg/dL |
| Creatinine | 0.35 mg/dL | read it through the Schwartz eGFR below: ≥90 at his height means about 0.5 or less |
| eGFR, bedside Schwartz (0.413 × height in cm ÷ creatinine) | 0.413 × 106 ÷ 0.35 = 125 mL/min/1.73 m² | ≥90 |
| C3 / C4 | 118 / 26 mg/dL | 90–180 / 16–47 mg/dL |
Q3The plan for Jalen
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 and C4, and no hematuria. He took ibuprofen for a week before the swelling began. What is the right plan?
Kidney biopsy first, because a lesion triggered by ibuprofen has to be proven in tissue
An ACE inhibitor alone for the proteinuria, with a repeat urine protein ratio in three months
IV albumin with furosemide to correct the albumin, adding steroids only if the edema persists
No ibuprofen; oral prednisone with pediatric nephrology, no biopsy, watching the response
Show answer and explanation · Link to this question
Correct answer: D
Learning point: His typical childhood nephrotic presentation supports initial oral glucocorticoids under pediatric nephrology without routine biopsy. This predicts steroid sensitivity; it does not prove minimal-change histology. Sustained hypertension, gross hematuria, low complement, AKI not explained by hypovolemia, syndromic features or steroid resistance prompt reconsideration; the NSAID exposure is removed but does not by itself establish causation. Why not the others: A overweights exposure without an atypical phenotype; B leaves the active syndrome untreated; C treats an albumin number rather than the underlying disease. Course reading: Evidence for this case
Prednisone starts that afternoon; pediatric nephrology sets the dose and the taper. His mother learns to limit salt, weigh him each morning and keep NSAIDs out of the house — acetaminophen is his fever and pain medicine now.
Q4Day nine
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 vomited twice. What is the right response?
Probable viral gastroenteritis: oral fluids at home and a call back if he cannot keep them down
Possible bacterial peritonitis: emergency department tonight for cultures and IV antibiotics
Probable steroid gastritis: add an acid blocker tonight and keep the prednisone dose unchanged
Tense ascites causing the pain: start furosemide tonight and recheck his weight tomorrow
Show answer and explanation · Link to this question
Correct answer: B
Learning point: A nephrotic child loses immunoglobulins and complement factors in the urine, which leaves him at increased risk of invasive bacterial infection, including pneumococcus, and he is on prednisone besides. Fever with diffuse abdominal tenderness in a child with ascites is bacterial peritonitis until cultures say otherwise: a same-night emergency. The same urine losses explain the other big complication — antithrombin and protein S go out while the liver makes more fibrinogen, so nephrotic children clot, which is one more reason not to over-diurese. Why not the others: A — gastroenteritis is a diagnosis of exclusion in a febrile nephrotic child; C — gastritis does not cause fever and peritoneal signs; D — a diuretic tonight thickens the blood and delays treatment of an infection. Course reading: Evidence for this case
Part 2 — Data
Answers for this section: Q5
The same week, an urgent care. Jalen's cousin Marcus, a 36-year-old Black man who works nights at a distribution center, has had three weeks of leg swelling and urine that "foams like a shaken soda"; he has gained 7 kg. He has not seen a doctor in six years. He takes no medicines — no NSAIDs, supplements or anabolic steroids — drinks little, does not use drugs, is sexually active and has never had an HIV test. He has heard about Jalen and asks whether he has "the same thing." The urgent-care note reads: "Nephrotic syndrome in an obese young man — probable primary FSGS. Consider prednisone. Refer."
Vitals: BP 150/94 (large adult cuff; repeat 148/92) · HR 82 · T 36.9 °C · SpO₂ 98% · weight 128 kg · height 183 cm (BMI 38.2).
Exam: Pitting edema to mid-thigh and puffy eyelids. No rash, no jaundice, no lymph node enlargement. Lungs clear, no jugular venous distension, heart regular.
| Drug | Dose | Route | Frequency | Indication |
|---|---|---|---|---|
| None | — | — | — | No prescription or over-the-counter medicines |
| Test | Result | Reference range |
|---|---|---|
| Sodium / potassium | 137 / 4.9 mEq/L | 135–145 / 3.5–5.0 mEq/L |
| Chloride / bicarbonate | 107 / 23 mEq/L | 98–107 / 22–29 mEq/L |
| BUN | 28 mg/dL | 7–20 mg/dL |
| Creatinine | 1.9 mg/dL (no earlier value) | 0.7–1.3 mg/dL |
| eGFR (CKD-EPI 2021) | 46 mL/min/1.73 m² — a steady-state estimate; with no earlier creatinine, repeat in 1–2 weeks before staging | ≥60 mL/min/1.73 m² |
| Albumin | 2.2 g/dL | 3.5–5.0 g/dL |
| Total cholesterol | 312 mg/dL | <200 mg/dL |
| Hemoglobin A1c | 5.6% | <5.7% |
| Urinalysis | protein 4+, blood 1+; 2–4 RBC/hpf of uniform shape; oval fat bodies; no casts | negative; 0–2 RBC/hpf |
| Urine protein-to-creatinine ratio | 11.2 g/g | <0.15 g/g |
Q5Marcus's first work-up
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 value, and an A1c of 5.6%. The urgent-care note says "probable primary FSGS — consider prednisone." What is the right next step?
Prednisone now for presumed primary FSGS, referring to nephrology if no response by 8 weeks
Obesity-related FSGS: a weight-loss program and an ACE inhibitor, with repeat labs in 3 months
HIV, hepatitis B and C, syphilis, ANA, C3/C4 today; ultrasound; nephrology this week
A kidney biopsy this week, sending the serologies after the pathologist has read the tissue
Show answer and explanation · Link to this question
Correct answer: C
Learning point: FSGS is a scar pattern: the same lesion comes from a primary podocyte disease or from injury by obesity, HIV, heroin, pamidronate or low nephron mass, and treatment depends on the cause; empiric steroids should not precede this evaluation. So every adult with new nephrotic syndrome gets the secondary-cause screen — HIV, hepatitis B and C, syphilis, ANA, complements, A1c, protein electrophoresis with free light chains — and an ultrasound before treatment; biopsy is nephrology's call after that. His weight is a weak explanation: obesity-related FSGS usually spares the albumin and the edema, and he has the full syndrome. Why not the others: A — a steroid before the screen may treat a cause that steroids worsen; B — anchors on his weight despite an albumin of 2.2 and edema to the thighs; D — the cause-directed screen and nephrology review can begin immediately alongside biopsy planning. Course reading: Evidence for this case
Part 3 — Course and Decisions
Answers for this section: Q6 · Q7
The screen and a renal ultrasound come back in 48 hours.
Q6Evidence update
Concordance-style practice: there is no expert panel behind this key, the teaching explanation. "Unchanged" means the finding does not move the hypothesis — not "I'm not sure."
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 and that both kidneys are enlarged (13.4 and 13.9 cm) and echogenic, this hypothesis becomes:
Much less likely
Less likely
Unchanged
More likely
Much more likely
Show answer and explanation · Link to this question
Correct answer: A
Learning point: Uncontrolled HIV with nephrotic proteinuria and enlarged echogenic kidneys strongly raises concern for HIV-associated nephropathy. Kidney size and echogenicity are nonspecific, and HIV can accompany other kidney lesions; biopsy may be needed. The finding shifts the working explanation away from an assumed primary FSGS, while treatment of HIV should begin promptly. Why not the others: B is reasonable if the learner emphasizes biopsy uncertainty; C ignores the newly identified secondary cause; D and E favor primary disease despite contrary evidence. Do not grade the degree as a validated probability. Course reading: Evidence for this case
The full screen (48 hours)
| Test | Result | Reference range |
|---|---|---|
| HIV-1/2 antigen/antibody | reactive | nonreactive |
| HIV-1 RNA (viral load) | 480,000 copies/mL | not detected |
| CD4 count | 190 cells/µL | 500–1,500 cells/µL |
| Hepatitis B surface antigen / hepatitis C antibody / syphilis antibody | negative / negative / nonreactive | negative / negative / nonreactive |
| ANA; C3 / C4 | negative; 124 / 30 mg/dL | negative; 90–180 / 16–47 mg/dL |
| Serum protein electrophoresis and free light chains | no monoclonal protein | none |
| Renal ultrasound | right kidney 13.4 cm, left 13.9 cm; both cortices brighter than the liver; no hydronephrosis | 10–12 cm; cortex less echogenic than liver |
Q7What Marcus starts
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 150/94. Which plan is right?
Prednisone at nephrotic doses now, since collapsing FSGS progresses too fast to wait for anything
Antiretrovirals now via the HIV clinic, plus an ACE inhibitor; nephrology decides on biopsy
Hold antiretrovirals until a biopsy proves HIVAN, in case the lesion is primary FSGS after all
A weight-loss program and an ACE inhibitor first, adding antiretrovirals if protein persists
Show answer and explanation · Link to this question
Correct answer: B
Learning point: HIVAN is driven by virus inside the podocytes, so the treatment is viral suppression: antiretroviral therapy started promptly, to suppress the virus and reduce progression risk; kidney recovery varies. The ACE inhibitor adds protein reduction and BP control; with a potassium of 4.9 and a creatinine of 1.9, both are rechecked within 1–2 weeks. Nephrology decides whether to biopsy — it can confirm HIVAN and exclude an HIV-related immune-complex GN — but the antiretrovirals do not wait for it. Why not the others: A — steroids are not first-line for HIVAN and are risky with a CD4 count under 200; C — waiting for tissue leaves the cause running; D — his weight is not what is injuring his podocytes. Course reading: Evidence for this case
Resolution and Teaching Points
Answers for this section: W1 · W2 · Q3 · Q4 · Q5 · Q6 · Q7
Jalen. In the emergency department his blood culture grew Streptococcus pneumoniae; IV antibiotics cleared the peritonitis and the prednisone continued. His dipstick turned protein-negative on day 16 — remission. Pediatric nephrology set the taper and, once he was well, added the extra pneumococcal vaccine that nephrotic children need. His parents know that at least half of children relapse, often with a cold, so they check his urine whenever he is ill or puffy and call early.
Marcus. Antiretroviral therapy, chosen by the HIV clinic for his kidney function, started within the week, with lisinopril; his potassium and creatinine were stable at two weeks, and nephrology biopsied him once his BP was controlled — HIV-associated nephropathy. Six months later his viral load is undetectable, his CD4 count is 410, his UPCR has fallen from 11.2 to 3.0 g/g, and his creatinine is 1.7 (eGFR 53). His partner has been tested.
Exposures that injure the glomerulus — the pairs to know
| Exposure | Lesion | First move |
|---|---|---|
| HIV, uncontrolled | HIVAN — collapsing FSGS; large, echogenic kidneys | Antiretroviral therapy |
| Hepatitis B | Membranous nephropathy | Antiviral treatment and coordinated nephrology/hepatology review before immunosuppression |
| Hepatitis C | MPGN or cryoglobulinemic GN — often low C4 | Antiviral therapy; severe cryoglobulinemic disease may need additional specialist treatment |
| NSAIDs | Minimal change disease, membranous; also interstitial nephritis | Stop the suspected drug and review safer analgesia |
| Lithium, pamidronate, heroin, interferon | FSGS or minimal change patterns | Stop or substitute with the prescriber |
| Hydralazine, propylthiouracil, levamisole-cut cocaine | ANCA vasculitis | Stop; same-day nephrology if the creatinine is rising |
Clinical Pearl — The typical child does not need a needle A typical young child with nephrotic syndrome can receive initial glucocorticoids without routine biopsy; minimal-change histology is likely, not proven. Atypical findings or steroid resistance change the work-up. Adult biopsy decisions depend on the suspected cause and available serology.
Clinical Pearl — Nephrotic children get infections and clots Urinary losses of immunoglobulin and complement leave them exposed to pneumococcus; losses of antithrombin and protein S make them clot. Fever with abdominal pain and ascites is peritonitis until proven otherwise. Vaccinate, do not over-diurese, and leave anticoagulation decisions to nephrology.
Clinical Pearl — FSGS is a pattern; find the cause before the steroid Obesity, HIV, heroin, pamidronate, reflux and low nephron mass all produce it, and secondary FSGS responds to removing the cause, not to immunosuppression. Obesity-related FSGS usually spares the albumin, so a full nephrotic syndrome in an obese adult still needs the screen.
Clinical Pearl — Bright and big is not bright and small Small echogenic kidneys support chronic disease; enlarged echogenic kidneys have several explanations, including HIV-associated disease. Size depends on body size and neither pattern establishes histology.
Clinical Pearl — Viral serologies in every nephrotic work-up HIV, hepatitis B and hepatitis C can produce several glomerular patterns. Identify and treat the infection; coordinate any immunosuppression with nephrology and the infection specialist.
Pitfall — Adult numbers in a child The adult nephrotic line (3.5 g a day) and the adult BP lines (120/80, 130/80) both misclassify a 4-year-old. Use the ratio scaled to body size and the height-percentile table.
Pitfall — Prednisone from the urgent care An empiric steroid for an adult's nephrotic syndrome, written before the HIV and hepatitis results, can treat the wrong disease and worsen the right one.
Concept Links
Answers for this section: W1 · W2 · Q3 · Q4 · Q5 · Q6 · Q7
Assigned reading: the explanations in this case and the question-linked course evidence guide. The objective map distinguishes tested decisions from concepts taught in explanations.
Concepts: glom-04, glom-07, glom-08, glom-09, glom-18, glom-19, glom-22, glom-23, glom-24, glom-25, htn-cardiorenal-17.