Methods

A total of 33 subjects was studied. Group I (Table 1) consisted of 12 family members without demonstrable cysts. The diagnosis of polycystic kidneys was based on a positive family history, drip (prolonged) infusion intra-venous pyelograms with tomography and, in some in-stances, renal arteriograms. Group II (Table 2) consisted of 13 patients with polycystic kidneys without renal insufficiency (GFR> 60 mI/mm). Group III (Table 3) con-sisted of eight patients with polycystic kidneys whose GFR was 10 mI/mm or less1. Patients in Group III were stable at the time of study and did not have manifestations of the uremic syndrome. All patients were admitted to the Baylor Clinical Research Center (CRC) for study after their in-formed consent had been obtained. Laboratory studies included hemograms, blood urea nitrogen, serum creatinine, sodium, potassium, chloride, bicarbonate, calcium, phos-phate and uric acid; urinalysis, urine cultures, 24-hour protein excretion and creatinine clearance were also per-formed. Hemoglobin electrophoresis was done on all black patients.

Patients without renal insufficiency were studied four to five days after admission to the CRC while on a diet containing at least 100 mEq of sodium per day and water ad libitum. Patients with a GFR of less than 10 mI/mm were given diets containing 30 g high biological value proteins. Dietary sodium intake had to be individualized for each of these patients (40 to 100 mEq) but studies were not performed until the time when sodium intake equaled urinary output and weight, blood urea nitrogen and serum creatinine had remained constant for at least three days.