Hereditary cystic kidney disease causing progressive enlargement and renal failure by middle age.
Also known as: ADPKD, polycystic kidney disease, PKD, PKD1, PKD2
Overview
An autosomal dominant systemic disorder characterized by progressive development and enlargement of bilateral renal cysts leading to massive nephromegaly and progressive loss of renal function. Caused by mutations in PKD1 (chromosome 16, ~78%) or PKD2 (chromosome 4, ~15%) encoding polycystin-1 and polycystin-2.
Epidemiology
Most common inherited kidney disease, prevalence ~1 in 400-1000. Accounts for ~5% of ESRD. PKD1 mutations cause earlier ESRD (median ~55 years) vs PKD2 (~75 years).
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Question 1RenalMedium
A 35-year-old female with autosomal dominant polycystic kidney disease (ADPKD) is referred for management. eGFR is 62 mL/min. Total kidney volume on MRI is 2,200 mL (Mayo Imaging Classification 1C). She has no pain or other complications. She asks about disease-modifying treatment to slow cyst growth and preserve renal function. Which of the following is the most appropriate disease-modifying therapy?
AFurosemide
BTolvaptan
CLisinopril
DSpironolactone
Reveal answer & full explanation
Correct answer: B — Tolvaptan
AFurosemide
BTolvaptan✓
CLisinopril
DSpironolactone
Why Tolvaptan is correct
Autosomal dominant polycystic kidney disease (ADPKD) results from mutations in PKD1 or PKD2 (encoding polycystin-1 and polycystin-2).
Tolvaptan is a selective vasopressin V2 receptor antagonist; V2 receptor activation raises intracellular cAMP, which drives cyst epithelial proliferation and fluid secretion, so V2 blockade slows cyst growth.
TEMPO 3:4 trial (NEJM 2012): tolvaptan reduced total kidney volume (TKV) growth by 49% and eGFR decline by 26% over 3 years.
Patient selection targets rapidly progressing disease (Mayo Class 1C-1E); this patient is Mayo Class 1C.
Why the others are wrong
Furosemide — Right-concept-wrong-mechanism: a loop diuretic reduces volume overload but has no disease-modifying effect on cyst growth in ADPKD.
Lisinopril — Confused-with BP management: an ACE inhibitor controls blood pressure and proteinuria in CKD (HALT-PKD targeted BP <110/75) but does not slow cyst growth.
Spironolactone — Anchoring on diuretics: a mineralocorticoid antagonist has no established disease-modifying role in ADPKD cyst growth.
Additional high-yield points
Tolvaptan side effects: aquaresis (polyuria, polydipsia, nocturia) and hepatotoxicity — requires a REMS program with monthly liver function tests (LFTs) for 18 months.
Contraindications: liver disease, pregnancy, inability to maintain adequate fluids.
A 30-year-old male has hypertension since age 25, hematuria, and a family history of kidney failure in his father at age 55. Renal ultrasound shows multiple bilateral kidney cysts. Which of the following best describes the mode of inheritance and the other organ that should be screened?
AAutosomal dominant; screen for cerebral artery aneurysms with MRA
BAutosomal recessive; screen for childhood oligohydramnios
CMitochondrial inheritance; screen for multi-organ involvement
DX-linked recessive; screen for sensorineural hearing loss
Reveal answer & full explanation
Correct answer: A — Autosomal dominant; screen for cerebral artery aneurysms with MRA
AAutosomal dominant; screen for cerebral artery aneurysms with MRA✓
BAutosomal recessive; screen for childhood oligohydramnios
CMitochondrial inheritance; screen for multi-organ involvement
DX-linked recessive; screen for sensorineural hearing loss
Why Autosomal dominant; screen for cerebral artery aneurysms with MRA is correct
This is autosomal dominant polycystic kidney disease (ADPKD): the most common inherited kidney disease, caused by mutations in PKD1 (85% of cases, more severe) or PKD2
Multiple bilateral cysts develop over decades; end-stage renal disease (ESRD) typically occurs by age 50-70
Berry (cerebral) aneurysms affect 5-10% of ADPKD patients; screening MRA is targeted to higher-risk patients (family history of intracranial aneurysm/SAH, prior SAH, or high-risk occupation) rather than performed universally
Why the others are wrong
Autosomal recessive; screen for childhood oligohydramnios — Autosomal recessive polycystic kidney disease (ARPKD) has childhood onset with oligohydramnios and Potter sequence; it does not fit this adult presentation
Mitochondrial inheritance; screen for multi-organ involvement — mitochondrial inheritance is not associated with polycystic kidney disease in this pattern
X-linked recessive; screen for sensorineural hearing loss — Alport syndrome is X-linked (or autosomal) with hematuria plus sensorineural hearing loss plus lenticonus; it does not cause bilateral cysts on ultrasound
Additional high-yield points
Extra-renal manifestations of ADPKD: hepatic cysts (most common extra-renal finding), mitral valve prolapse, diverticulosis, abdominal hernias
Treatment: blood pressure control with ACE inhibitor (ACEi) or angiotensin receptor blocker (ARB); tolvaptan (V2 receptor antagonist) slows cyst progression
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Modified Ravine ultrasound criteria for at-risk individuals: Age 15-39: ≥3 cysts (unilateral or bilateral). Age 40-59: ≥2 cysts in each kidney. Age ≥60: ≥4 cysts in each kidney. Absence of criteria in PKD1 family >40 yr essentially excludes disease.
Labs
BMP — eGFR may be preserved well into adulthood
Urinalysis — hematuria during cyst hemorrhage; mild proteinuria
Lipid panel, A1c for cardiovascular risk
Genetic testing (PKD1, PKD2, GANAB) — confirms diagnosis when imaging equivocal or for early pre-symptomatic diagnosis
Imaging
Renal ultrasound — first-line screening; modified Ravine criteria diagnose ADPKD based on age and cyst number
MRI or CT — better characterization, total kidney volume (TKV) measurement for prognosis (Mayo classification)
MR angiography for screening intracranial aneurysm in patients with family history of aneurysm/SAH or high-risk occupation
Diagnostic algorithm
Feature
ADPKD
ARPKD
Inheritance
Autosomal dominant
Autosomal recessive
Gene
PKD1 (~78%), PKD2 (~15%)
PKHD1 (fibrocystin)
Typical presentation age
3rd-4th decade adult
Infancy/childhood
Kidney appearance
Large cysts of varying sizes, bilateral
Diffuse small cysts, ductal pattern
Hepatic involvement
Hepatic cysts (asymptomatic usually)
Congenital hepatic fibrosis, portal HTN
Extra-renal
Aneurysms, MVP, diverticula, hernias
Pulmonary hypoplasia (neonatal)
Prognosis
ESRD median 55 (PKD1) / 75 (PKD2)
30-50% mortality in 1st year; 70% survival to 15 yr
Comparison of ADPKD and ARPKD — inheritance, presentation, and prognosis.
Treatment
First-line
Aggressive BP control — target <120/75 in CKD stages 1-2 (HALT-PKD); ACEi (lisinopril, ramipril, enalapril) or ARB (losartan, valsartan, irbesartan) first-line
Tolvaptan — vasopressin V2 receptor antagonist; FDA-approved for adults at risk of rapid progression (eGFR 25-65, evidence of progression, Mayo class 1C-1E); slows eGFR decline and TKV growth
High water intake (>2.5-3 L/day) to suppress vasopressin (theoretical benefit; recommended outside tolvaptan)
Low sodium diet, normal protein intake, weight control
Statin if dyslipidemia or CVD risk; avoid nephrotoxins
Cyst infection: lipophilic antibiotics (fluoroquinolones — ciprofloxacin, levofloxacin; trimethoprim-sulfamethoxazole) for ≥4-6 weeks; drainage if no response
Stones: management as for general urolithiasis; alpha-blocker, hydration, surgical removal as needed
Aneurysm screening: MRA in patients with family history of intracranial aneurysm or SAH; treat aneurysms >7 mm or symptomatic
RRT/transplant for ESRD — transplant outcomes equivalent to general population; native nephrectomy may be needed pre-transplant if massive nephromegaly
Complications
Hypertension (often early, before significant CKD)
Progressive CKD/ESRD by 4th-7th decade
Intracranial aneurysms (5-10%, higher with family history); subarachnoid hemorrhage
Cyst hemorrhage, infection, stones
Hepatic cysts (rarely symptomatic), pancreatic and seminal vesicle cysts
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