Adult Polycystic Kidney Disease

A 38-year-old woman was hospitalized because of bilateral flank pain and gross hema- turia. Her medical history included autosomal dominant (adult) polycystic kidney disease (ADPKD). Her father had end-stage renal disease.

Physical examination revealed systolic and diastolic hypertension and tender- ness in both costovertebral angles. Laboratory findings included a slight leukocytosis and serum creatinine and urea concentrations of 2.5 mg/dL and 90 mg/dL, respectively. Results of urinalysis showed numerous erythrocytes and protein. Ultrasonography demonstrated multiple cysts in both kidneys and no signs of urolithiasis. A CT scan also showed multiple cysts that project- ed beyond the renal contours, causing a bosselated appearance of the kidney; small cysts were visible throughout the liver as well.

The autosomal dominant form of PKD is an important cause of renal failure, accounting for 10% to 15% of patients who receive hemodialysis. The incidence is about 1 in 500 to 1000. Two genes for ADPKD have been localized: PKD1 on chro- mosome 16 and PKD2 on chromosome 4. The trait is transmitted in an autosomal dominant fashion; 50% of an affected individual’s off- spring will be affected. Most cases are identified when patients are be- tween 30 and 50 years of age.

A number of associated anomalies are common, including cysts of the liver, pancreas, spleen, and lungs; aneurysms of the circle of Willis; colonic diverticula; and mitral valve prolapse. In this case, except for the small asymptomatic cysts in the liver, no other extrarenal manifestations were found.

There are several theories about the pathogenesis of ADPKD. One of these suggests that a defect in the basement membrane of the tubules accounts for cyst development. Another postulates a defect in one of the proteins of the supportive extracellular connective tissue matrix, and a third proposes that tubular epithelial cell hyperplasia is the major component of cyst development.

Complications of ADPKD, such as intracranial hemorrhage, can be reduced significantly by controlling the renin-mediated hypertension. The severity of flank pain and the rate of renal function deterioration seem to correlate with the rate of cyst growth. Thus, laparoscopic un- roofing of the larger cysts is recommended.