Polycystic kidney disease is an inherited disorder characterized by multiple, bilateral, grapelike clusters of fluid-filled cysts that enlarge the kidneys, compressing and eventually replacing functioning renal tissue. The disease affects males and females equally and appears in distinct infantile and adult-onset forms. The adult form, autosomal dominant polycystic kidney disease, occurs in nearly 1 in 1,000 persons and accounts for about 10% of end-stage renal disease in the United States. Autosomal recessive polycystic kidney disease occurs in 1 in 10,000 to 1 in 40,000 live births. Renal deterioration is more gradual in adults than infants, but in both age-groups, the disease progresses relentlessly to fatal uremia.
The rare infantile form of polycystic kidney disease causes stillbirth or early neonatal death due to pulmonary hypoplasia. The adult form has an insidious onset. It usually becomes obvious between ages 30 and 50; rarely, it remains asymptomatic until the patient is in his 70s.
The prognosis in adults is extremely variable. Progression may be slow, even after symptoms of renal insufficiency appear. After uremia symptoms develop, polycystic disease usually is fatal within 4 years, unless the patient receives dialysis.
· Autosomal dominant trait (adult type); three genetic variants identified
· Autosomal recessive trait (infantile type)
Grossly enlarged kidneys are caused by multiple spherical cysts, a few millimeters to centimeters in diameter, that contain straw-colored or hemorrhagic fluid. The cysts are distributed evenly throughout the cortex and medulla. Hyperplastic polyps and renal adenomas are common. Renal parenchyma may have varying degrees of tubular atrophy, interstitial fibrosis, and nephrosclerosis. The cysts cause elongation of the pelvis, flattening of the calyces, and indentations in the kidney.
Accompanying hepatic fibrosis and intrahepatic bile duct abnormalities may cause portal hypertension and bleeding varices. In most cases, about 10 years after symptoms appear, progressive compression of kidney structures by the enlarging mass causes renal failure.
Cysts also form on the liver, spleen, pancreas, or ovaries. Intracranial aneurysms, colonic diverticula, and mitral valve prolapse also occur.
Signs and symptoms
· Potter facies—pronounced epicanthic folds; pointed nose; small chin; floppy, low-set ears
· Huge, bilateral, symmetrical masses on the flanks that are tense and can't be transilluminated
· Signs of respiratory distress, heart failure and, eventually, uremia and renal failure
· Lumbar pain
· Widening abdominal girth
· Swollen or tender abdomen, worsened by exertion and relieved by lying down
· Grossly enlarged kidneys on palpation
Diagnostic test results
· Excretory or retrograde urography shows enlarged kidneys, with elongation of the pelvis, flattening of the calyces, and indentations in the kidney caused by cysts.
· Excretory urography of the neonate shows poor excretion of contrast medium.
· Ultrasonography, tomography, and radioisotope scans show kidney enlargement and cysts; tomography, computed tomography, and magnetic resonance imaging show multiple areas of cystic damage.
· Urinalysis detects hematuria, bacteriuria, or proteinuria.
· Creatinine clearance tests show renal insufficiency or failure.
· Antibiotics for infections
· Analgesics for abdominal pain
· Adequate hydration to maintain fluid balance
· Antihypertensives, diuretics to control blood pressure
· Changes in diet and exercise
· Surgical drainage of cystic abscess or retroperitoneal bleeding
· Nephrectomy not recommended (polycystic kidney disease occurs bilaterally, and infection could recur in the remaining kidney)
· Dialysis or kidney transplantation for progressive renal failure