Polycystic kidney disease
Polycystic kidney disease is a genetic cystic disorder causing progressive bilateral renal cyst formation, most commonly autosomal dominant polycystic kidney disease (ADPKD) from a PKD1 or PKD2 mutation, leading to hypertension, hematuria, and end-stage kidney disease in more than half of patients by age 70. Management centers on blood pressure control with renin-angiotensin blockade and, in patients at risk for rapid progression, vasopressin V2-receptor blockade with tolvaptan.
- Topic reviewThe full article, organized the way the exam asks it.
- ABIM-format MCQsVignettes with an explanation for every wrong answer.
- Key factsThe numbers and thresholds worth memorizing, up front.
- AI tutorMedBrain answers the question you're stuck on.
What this article covers
- Overview
Polycystic kidney disease is a genetic disorder of progressive, bilateral renal cyst formation that replaces normal kidney architecture and ultimately impairs kidney function.
- Epidemiology
ADPKD is the most common hereditary kidney disease, occurring equally in males and females; diagnosis is often delayed without a known family history, since onset is typically silent for decades and…
- Risk factors
A family history of ADPKD, the dominant risk factor given autosomal dominant inheritance with more than 90% penetrance.
- Pathophysiology
Polycystin 1 and polycystin 2 normally regulate tubular epithelial cell growth; loss of function from a PKD1 or PKD2 mutation disrupts this regulation.
- Clinical features
Hypertension is often the first sign of ADPKD, frequently preceding gross structural or functional abnormalities.
- Differential diagnosis
Simple (benign) renal cysts: common with aging and few in number; a single simple cyst in an adult does not suggest ADPKD.
- Diagnosis
In a patient with a family history of ADPKD, the diagnosis is established by renal ultrasonography using age-specific cyst-count criteria: 3 or more cysts in one or both kidneys for ages 15-39 years…
- Management
First, control blood pressure with renin-angiotensin system blockade, targeting below 110/75 mm Hg in younger patients with preserved kidney function (below 130/80 mm Hg once eGFR is reduced), since…
- Complications
Progressive decline in kidney function to ESKD, occurring in more than half of ADPKD patients by age 70 years, the dominant long-term complication.
- Prognosis
More than 50% of ADPKD patients progress to ESKD by age 70 years, though the rate varies with genotype (PKD1 truncating mutations progress fastest) and other rapid-progression risk factors.
- Prevention
Offer genetic counseling to families with a known PKD1 or PKD2 mutation before pregnancy, given the autosomal dominant inheritance with more than 90% penetrance.
Read the whole article
Subscribing to Internal Medicine opens every article, the full question bank and MedBrain, on the web, iPhone and Android.
Related articles
- Nephrolithiasis
Nephrolithiasis affects 7-11% of the US population, most often as calcium oxalate stones, and presents as colicky flank pain radiating to the groin with hematuria. Noncontrast CT confirms the diagnosis and stone size drives management: hydration, NSAID/opioid analgesia, and alpha-blocker expulsive therapy for stones under 10 mm, urologic intervention for larger, infected, or obstructing stones.
- Approach to hematuria
Hematuria is present in urine when at least 3 erythrocytes per high-power field are seen on microscopy, and the first branch point is glomerular versus nonglomerular bleeding, based on erythrocyte morphology and casts. Gross hematuria always requires urologic evaluation and cystoscopy, asymptomatic microscopic hematuria is risk-stratified by American Urological Association criteria to select repeat testing, imaging, or cystoscopy, and glomerular hematuria is treated with disease-specific immunosuppression after biopsy.
- Alport syndrome
Alport syndrome (hereditary nephritis) is a genetic type IV collagen disorder causing progressive glomerulonephritis with sensorineural hearing loss and ocular abnormalities, most often X-linked, that progresses to end-stage kidney disease in nearly all affected males. Management is supportive with renin-angiotensin system blockade to slow progression; there is no disease-specific therapy.
- Rapidly progressive glomerulonephritis
Rapidly progressive glomerulonephritis is a clinical syndrome defined by at least a 50% decline in glomerular filtration rate over days to weeks with extensive glomerular crescents on biopsy, most often from ANCA-associated, anti-glomerular basement membrane, or immune-complex glomerulonephritis. Untreated disease progresses to dialysis within days to weeks, so kidney biopsy and etiology-directed immunosuppression must begin urgently.