Case 15: The Family Discovery

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Session S5 · 2026-11-03 · in-session · 37 min Anchor: Integrative review — ADPKD, cysts and incidental findings followed over fifteen years · Integrates: hematuria routing in a cystic kidney, complicated UTI in a structural kidney, imaging and the contrast rules, blood pressure, family screening, the Alport / TBMN / ADTKD contrast, and CKD referral, transplant and KRT planning One-line hook: You will meet this family in primary care: the man with blood in his urine, the brother who wants a scan tomorrow, the sister with "just a cyst." Three questions, three different answers — and the wrong one can cost an insurance policy, a week in hospital, or a kidney before dialysis.

Learning Objectives

Answers for this section: W1 · W2 · W3 · Q4 · Q5 · Q6 · Q7 · Q8 · Q9 · Q10 · Q11 · Q12

1. Route flank pain with gross hematuria in a polycystic kidney among a cyst bleed, a stone and an infection, and choose the imaging that answers each question.
2. Apply the age-based ultrasound criteria for ADPKD to a patient and two relatives, and counsel an at-risk adult before screening, including when genetic testing replaces imaging.
3. Plan first-line care for new ADPKD: analgesia without NSAIDs, the first blood pressure drug and its monitoring, and aneurysm screening — for whom, and with which test.
4. Manage a febrile polycystic kidney as a complicated urinary infection, and interpret a culture result in light of where the infection sits.
5. Prepare a patient for late CKD: transplant timing, a related living donor, KRT education, vein preservation and the contrast rules by eGFR (the nephrology referral triggers are discussed, not tested).

Warm-Up (individual commit before the case)

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Three readiness items from Sessions 3 and 4. Cards up, one sentence each, no discussion.

Part 1 — Presentation

Answers for this section: Q4 · Q5 · Q6

Mr. K. is 34. He teaches high-school chemistry and coaches wrestling, and he has not seen a doctor since a college sports physical. He walks into urgent care on a Saturday morning with two days of right flank pain — a dull ache at first, then waves of sharper pain last evening — and this morning his urine was "the color of cranberry juice." No fever, chills, burning or trouble passing urine. He vomited once last night. He took ibuprofen 600 mg three times yesterday from the bottle in the wrestling room. No previous kidney stones. He does not smoke; he drinks two or three beers on a weekend.

Ask about the family and the case changes shape. His father started dialysis at 55 and died at 58 of "a bleed in his brain" — a ruptured intracranial aneurysm, a weak spot in a brain artery that balloons and bursts. His father's mother "had kidney trouble" and died in her sixties. His mother is healthy. He has a sister, 38, and a brother, 19, a college sophomore. Nobody told him what his father's kidney disease was called, or suggested he be checked. A work health fair two years ago said his pressure "ran a little high."

Hematuria is blood in the urine — gross when you can see it, microscopic when only the lab can. A cyst is a fluid-filled sac with a thin wall. In autosomal dominant polycystic kidney disease (ADPKD), hundreds of cysts grow for decades, stretch the kidneys to several times their normal size and squeeze the working tissue; many patients reach kidney failure in middle age. Autosomal dominant means one faulty copy of the gene is enough: each child of an affected parent has a 50 % chance of inheriting it, and the disease does not skip a generation, even when the diagnosis does.

Vitals: BP 146/92 seated, repeated after five minutes 144/90 · Pulse 84 · T 37.1 °C · Respiratory rate 16 · Weight 92 kg · Height 183 cm (BMI 27.5).

Exam: Uncomfortable but not toxic. Mild right costovertebral-angle tenderness, none on the left. Abdomen soft; both flanks are full and both kidneys are palpable — a kidney you can feel in a man this size is an enlarged kidney. No bruit. Heart, lungs and neurological exam normal; no edema, no headache.

The urgent-care clinician orders a renal ultrasound that afternoon for the palpable kidneys. Renal ultrasound: right kidney 16.8 cm, left 16.2 cm (normal length 9–13 cm); more than ten cysts in each kidney, the largest 4.1 cm at the right upper pole; no hydronephrosis; bladder normal. Liver: four simple cysts, the largest 2.5 cm.

No prescription medications. No allergies.

Does he have ADPKD? The age-based ultrasound criteria (Pei unified criteria, 2009) Simple cysts become more common with age, so the number that makes the diagnosis in someone with an affected parent or sibling depends on age:

Age	Diagnostic	Excludes
15–39	≥3 cysts in total (one or both kidneys)	— (a negative scan is not final before 40)
40–59	≥2 cysts in each kidney	fewer than 2 cysts in total
≥60	≥4 cysts in each kidney	fewer than 2 cysts in total

Mr. K. is 34 with an affected father and more than twenty cysts: he meets the criteria many times over.

Pause — commit before the reveal

Part 2 — Data

Answers for this section: Q7 · Q8 · Q9

The non-contrast CT is done that evening; the blood and urine tests come back that night and the urine culture two days later. Walk the tables in order and ask what each result excludes before asking what it proves.

Serum chemistry and blood count (urgent care, age 34)

Urinalysis

Non-contrast CT, abdomen and pelvis (stone protocol): Both kidneys markedly enlarged (right 17.0 cm, left 16.4 cm) and replaced by innumerable cysts, more than ten in each kidney. No calculus in either kidney, either ureter or the bladder. No hydronephrosis. The 4.1-cm right upper-pole cyst is denser than the others — the appearance of recent bleeding into the cyst. No perinephric fluid or stranding. Four hepatic cysts, largest 2.5 cm.

What the data support. No stone or hydronephrosis is seen, and the clinical course, stable hemoglobin and dense cyst favor cyst hemorrhage. The nonglomerular urine pattern and lack of systemic infection signs make competing diagnoses less likely; they do not prove their absence. Confirm that bleeding resolves, and reassess persistent, atypical or recurrent prolonged symptoms.

The plan from urgent care. Acetaminophen, fluids, no NSAIDs. A home blood-pressure cuff: the week's average came back 142/90, so lisinopril 10 mg daily started on day 6; the BMP at two weeks showed creatinine 1.20 (a 7 % rise — expected) and potassium 4.4. Nephrology referral within a month — polycystic kidneys are "abnormal kidney imaging," a referral trigger on their own. Brain MRA for the family history. Repeat UACR once the urine is clear. A written summary for his sister and brother.

Then the family calls. His brother, 19, phones Monday: he has read about the disease all weekend and wants "the scan tomorrow." His sister, 38, had an abdominal ultrasound for gallstones last month; the report mentions "a 2.0-cm simple cyst, left kidney: thin wall, no septations, anechoic (fluid-dark, no internal echoes)." Her creatinine was 0.8 mg/dL (eGFR 97 for a 38-year-old woman), blood pressure 116/72, urinalysis bland. She wants to know whether she has what her brother has.

Pause — commit before the reveal

Part 3 — Course and Decisions

Answers for this section: Q10 · Q11 · Q12

Seven years pass. Nephrology took him on at 34. The brain MRA was negative; a repeat is booked for 44. On lisinopril 40 mg his home readings run 124–128 over 76–80. The UACR, repeated with clear urine, was 38 mg/g and has drifted to 90. His creatinine has crept from 1.12 to 1.30: eGFR 71 at 41, a loss of about 2.4 mL/min a year. His brother's ultrasound was negative at 19 and again at 24. His sister's scan at 40 still showed the one cyst, supporting exclusion of typical familial PKD1/PKD2 disease after genetic counseling; unusual familial variants or discordant findings would require a different evaluation. Mr. K. has had two more cyst bleeds, both managed at home and both cleared on the follow-up urinalysis.

Age 41, a Tuesday night in February. He arrives in the emergency department with eighteen hours of fever to 39.0 °C, rigors, right flank pain unlike his bleeds — constant, deep, worse when the car hit a pothole — and pink urine. No dysuria, urethral discharge, new partner, catheter or recent procedure. No antibiotic. He looks ill.

Vitals: BP 112/70 · Pulse 108 · T 39.0 °C · Respiratory rate 20 · SpO₂ 97 % on room air · Weight 94 kg.

Exam: Flushed, shivering, oriented. The right kidney, always palpable, is now exquisitely tender to percussion; the left flank is full but non-tender. Abdomen otherwise soft. No rash, joint swelling or murmur. Prostate normal and non-tender.

Labs (emergency department, age 41)

Urinalysis: SG 1.018; pH 6.0; blood 2+; protein trace; leukocyte esterase trace; nitrite negative. Microscopy: RBC 20–30/hpf, isomorphic; WBC 5–10/hpf; no casts; no bacteria seen.

Non-contrast CT abdomen and pelvis (stone protocol), 22:40: Kidneys 19.5 cm and 20.2 cm, innumerable cysts. No calculus. No hydronephrosis. No perinephric collection or gas. Several right-sided cysts are denser than water, as on prior studies. Radiologist's comment: no single cyst can be labeled infected on a non-contrast study.

Reading the room. The three-way differential from age 34 is back with the thermometer pointing the other way — pyelonephritis (infection of the collecting system), an infected cyst, or an infected stone — and the CT has removed the stone and the obstruction.

Pause — commit before the reveal

He is admitted. Blood cultures ×2 and a urine culture are drawn at 23:00; ceftriaxone 1 g IV follows at 23:10, and the lisinopril is held. Nephrology's plan on morning rounds: if he is still febrile at 48–72 hours, a contrast CT and a switch to a drug that reaches cyst fluid.

Hospital day 2, 48 hours in. Temperature still 38.8 °C after two doses of ceftriaxone. Repeat WBC 14.9 ×10³/µL, CRP 210 mg/L, creatinine 1.32. Urine culture: no growth at 48 hours. Blood cultures: no growth yet.

Eight more years. The contrast CT at 72 hours — low-risk at an eGFR of 71 — showed a 5-cm right lower-pole cyst with a thick, enhancing wall: the infected one. The blood cultures stayed sterile. Six weeks of a fluoroquinolone cured it; the fever broke on day five. At 42 his nephrologist offered tolvaptan, a nephrology-prescribed vasopressin blocker that slows kidney growth in adults progressing fast, with monthly liver tests for the first 18 months. He declined: it brings constant thirst and nights up passing urine. His kidneys kept growing. His brother screened negative again at 29 and at 34.

Age 49, nephrology clinic. He feels well — some fatigue, no nausea, no itch, no metallic taste, urinating normally. BP 126/78 on two drugs. Kidneys 23.1 cm and 23.6 cm on last year's ultrasound. The eGFR that was 71 at 41 is 22: a loss of about 6 mL/min a year over eight years, faster than the 5 mL/min-per-year referral trigger on its own.

Labs (nephrology clinic, age 49)

Reading the room, again. G4 A3 is a red cell of the KDIGO grid. He has been followed since 34, so each abnormal value already has a plan.

Resolution and Teaching Points

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The transplant center saw him within a month. Mr. K.'s own genetic test found the family's PKD1 variant; his brother tested negative for it and cleared the donor work-up at 35. Mr. K. received his brother's kidney at 50, at an eGFR of 13, never having been dialyzed. The chart banner his nephrologist wrote when he reached G4 still travels with him: ADPKD: no NSAIDs; iodinated contrast when it changes management, with isotonic fluid if eGFR <30; gadolinium group II only; no lines in the left arm.

Other families, other patterns — the debrief table. Not every inherited kidney disease is cystic. Three more patterns to recognize — and to send for genetics or reassurance rather than round the urology circuit again:

Clinical Pearl — Three causes of blood in a cystic kidney Bleeding into a cyst, a stone, an infection. The thermometer separates the third from the first two; the non-contrast CT separates the first two from each other. Ultrasound finds the cysts and the hydronephrosis but misses many ureteral stones — it is the screening test, not the colic test.

Clinical Pearl — The number you need depends on the age Fifteen to 39: three cysts in total. Forty to 59: two in each kidney. Sixty and over: four in each kidney. Exclusion has its own age — fewer than two cysts at 40 or older — so a negative scan at 19 is provisional. Age cuts both ways: one cyst at 38 is unremarkable, while bilateral cysts at 25 are a diagnostic question even without a family history.

Clinical Pearl — Screening is a conversation before it is a scan Eighteen or older, the relative's own decision, with the 50 % prior risk, the record and insurance consequences of a positive result, and the repeat plan after a negative one laid out first. Genetic testing is for equivocal imaging, a potential donor, family planning, or a presentation that does not fit.

Clinical Pearl — The infected cyst can have a clean urine A cyst may not communicate with the collecting system, so urine cultures can be negative despite infection. Hospitalize patients with sepsis or inability to manage safely as outpatients; obtain cultures without delaying treatment, seek cyst-penetrating therapy early and reassess persistent fever. Negative urine culture does not rule out pyelonephritis.

Clinical Pearl — The contrast rules travel with the eGFR Weigh the diagnostic benefit, agent and kidney status. Necessary IV iodinated contrast is not automatically forbidden in AKI or eGFR below 30; consider isotonic saline prophylaxis when appropriate and not contraindicated. Stable eGFR ≥30 generally carries lower risk, with selected additional precautions at 30–44. ACR–NKF and FDA-label metformin withholding policies differ; follow the stated institutional policy. When contrast MRI is needed, group II gadolinium has very low, not zero, NSF risk; avoid higher-risk agents when a suitable safer agent is available.

Pitfall — "It's the cysts" Attributing flank pain and hematuria to the polycystic kidneys without excluding a stone, or without confirming on a follow-up urinalysis that the blood actually cleared. The cysts are the reason he bleeds; they are also the reason he forms stones and gets infected, and they do not protect him from bladder cancer at 60.

Pitfall — A short oral course for a febrile man with a structural kidney Nitrofurantoin for "cystitis," or a week of an oral quinolone for "outpatient pyelo," in a rigoring man whose kidney is a bag of cysts. Complicated infections are admitted, cultured, treated intravenously, and re-imaged when they do not improve.

Concept Links

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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: ckd-08, ckd-10, ckd-21, ckd-22, ckd-24, glom-06, htn-cardiorenal-07, structural-01, structural-05, structural-09, structural-10, structural-12, structural-14, structural-15.