Polycystic kidney disease
An inherited disorder, polycystic kidney disease is characterized by multiple, bilateral, grapelike clusters of fluid-filled cysts that grossly enlarge the kidneys, compressing and eventually replacing functioning renal tissue. This disease appears in two distinct forms.
The infantile form causes stillbirth or early neonatal death. A few infants with this disease survive for 2 years and then develop fatal renal, heart, or respiratory failure.
The adult form begins insidiously but usually becomes obvious between ages 30 and 50; rarely, it doesn’t cause symptoms until the patient is in his seventies. In the adult form, renal deterioration is more gradual but, as in the infantile form, progresses relentlessly to fatal uremia.
The prognosis in adults varies. Progression may be slow, even after symptoms of renal insufficiency appear. However, after uremic symptoms develop, polycystic kidney disease is usually fatal within 4 years, unless the patient receives treatment with dialysis, a kidney transplant, or both.
Causes
Although both types of polycystic kidney disease are genetically transmitted, the incidence in two distinct age-groups and different inheritance patterns suggest two unrelated disorders. The infantile type appears to be inherited as an autosomal recessive trait; the adult type, as an autosomal dominant
trait. Both types affect males and females equally.
trait. Both types affect males and females equally.
Signs and symptoms
Clinical features vary with the form of disease.
Infantile form
The neonate with infantile polycystic disease may have pronounced epicanthal folds, a pointed nose, a small chin, and floppy, low-set ears (Potter facies). Signs of respiratory distress and heart failure may be evident. Eventually, he develops uremia and renal failure. Accompanying hepatic fibrosis may cause the development of portal hypertension and bleeding varices.
Adult form
Adult polycystic kidney disease is commonly asymptomatic while the patient is in his thirties and forties but may induce nonspecific signs and symptoms, such as hypertension, polyuria, and urinary tract infection. Later, the patient develops overt signs and symptoms related to the enlarging kidney mass, such as lumbar pain, widening girth, and a swollen or tender abdomen. Such abdominal pain is usually worsened by exertion and relieved by lying down.
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