Polycystic Kidney Disease

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 two distinct forms. The rare infantile form causes stillbirth or early neonatal death. The adult form has an insidious onset but usually becomes obvious between ages 30 and 50; rarely, it may not cause symptoms until the patient is in his 70s. Renal deterioration is more gradual in adults than in infants, but in both age-groups the disease progresses relentlessly to fatal uremia.

The prognosis in adults varies widely. Progression may be slow, even after symptoms of renal insufficiency appear. When uremic symptoms develop, polycystic disease usually is fatal within 4 years unless the patient receives dialysis.

Causes

This disease appears to occur all over the world among all socioeconomic and ethnic groups.

Autosomal dominant PKD is the most common inherited disease in the United States. People get the disease from a parent who has PKD. If one parent has autosomal dominant PKD, each child has a 50/50 chance of inheriting the disease. In autosomal recessive PKD, parents may have no symptoms but still carry a recessive gene for the disease. If both parents have this recessive gene, one-fourth of the children can inherit the disease.

Signs and Symptoms

The most common symptom of PKD is high blood pressure. Other symptoms are:

• Pain in the back and side
• Blood in the urine
• Frequent kidney infections

Not all patients will have all of these symptoms.

Diagnostic tests

In a patient with polycystic disease, excretory or retrograde urography typically reveals enlarged kidney with elongation of the pelvis, flattening of the calyces, and indentations caused by cysts. Excretory urography of the neonate shows poor excretion of com medium.

Ultrasonography, tomography, and radioisotopic scans show kidney enlargement and cysts; tomography, computed tomography, and magnetic resonance imaging show multiple areas of cystic damage.

Urinalysis and creatinine clearance tests - non specific tests that evaluate renal function - indicate abnormalities.

Diagnosis must rule out renal tumors.

Treatment

Polycystic kidney disease can't be cured. The prirmary goal of treatment is to preserve renal parenchyma and prevent pyelonephritis. Progressive renal failure requires treatment similar to that for other type of renal disease, including dialysis or, rarely, kidney transplantation.

When adult polycystic kidney disease is discovered in the asymptomatic stage, careful monitoring is required, including urine cultures and creatinine clearance tests every 6 months. When urine culture reveals infection, the patient needs prompt and vigorous antibiotic treatment even if he has no symptoms.

As renal impairment progresses, selected patients may undergo dialysis, transplantation, or both. Cystic abscess or retroperitoneal bleeding may necessitate surgical drainage; intractable pain (an uncommon symptom) may require surgery. Nephrectomy usually isn't recommended because this disease occurs bilaterally and the infection could recur in the remaining kidney.