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.

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.

Mean serum creatinine levels did not differ between the ADPKD (0.6 ± 0.2 mg/dL [51.1 ± 20.4 μmol/L]) and control groups (0.7 ± 0.2 mg/dL [59.8 ± 15.3 μmol/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.

Therefore, the high GFR measurements represent early hyperfiltration in children and adolescents with ADPKD, which may give a rationale to start ACE inhibitor therapy.