Patients with autosomal dominant polycystic kidney disease hyperfiltrate early in their disease.

BACKGROUND: Autosomal dominant polycystic kidney disease (ADPKD) ranks among the most common genetic disorders. The development of end-stage renal failure usually is after the fourth decade of life. Angiotensin-converting enzyme (ACE) inhibitors often are used as agents to slow the progression of renal failure, although their effectiveness and starting point in ADPKD remain unclear.
METHODS: We measured technetium 99m diethylenetriamine pentaacetic acid glomerular filtration rate (GFR) and serum cystatin C (Cys-C) levels in 18 children with ADPKD and 41 control patients. Data are given as mean +/- SD. Mean age was 9.8 +/- 5.9 years, mean height was 137.5 +/- 34.3 cm, and mean weight was 39.2 +/- 22.8 kg in the ADPKD group, not significantly different from controls, with an average age of 10.4 +/- 4.9 years, height of 138.0 +/- 26.1 cm, and weight of 38.0 +/- 16.8 kg.
RESULTS: Mean serum creatinine levels did not differ between the ADPKD (0.6 +/- 0.2 mg/dL [51.1 +/- 20.4 micromol/L]) and control groups (0.7 +/- 0.2 mg/dL [59.8 +/- 15.3 micromol/L]; P = 0.19). Mean GFR was 142 +/- 33.2 mL/min/1.73 m2 in the ADPKD group, significantly greater than that in controls (110 +/- 12 mL/min/1.73 m2; P < 0.0001). Mean Cys-C level for the ADPKD group was 0.71 +/- 0.11 mg/L, significantly lower than that of controls (0.81 +/- 0.12 mg/L; P = 0.0011). No patient with ADPKD had hypertension, and only 1 patient had minimal microalbuminuria. Although renal length on ultrasound was significantly increased, there was no correlation between renal length and GFR or number of cysts.
CONCLUSION: Therefore, the high GFR measurements represent early hyperfiltration in children and adolescents with ADPKD, which may give a rationale to start ACE inhibitor therapy.