Factors relating to urinary protein excretion in children with autosomal dominant polycystic kidney disease

Abstract

Adults with autosomal dominant polycystic kidney disease (ADPKD) who have overt proteinuria (>300 mg/d) have higher mean arterial pressures, lower creatinine clearances, larger renal volumes, and a more aggressive course of renal disease than ADPKD patients without proteinuria. This study examines the relationship between proteinuria and microalbuminuria and similar factors in ADPKD children. A total of 189 children from 81 ADPKD families was included in the analysis. The ADPKD children (n = 103) had significantly greater urine protein excretion rates than the non-ADPKD children (n = 86) (3.9 ± 0.3 versus 2.8 ± 0.2 mg/m2 per h, P < 0.001). Children with severe renal cystic disease (>10 cysts; n = 54) had greater protein excretion than those with moderate disease (≤10 cysts; n = 49) (4.4 ± 0.5 versus 3.3 ± 0.2 mg/m2 per h, P < 0.05). The ADPKD children had significantly greater albumin excretion rates than the non-ADPKD children (32 ± 6 versus 10 ± 2 mg/m2 per 24 h, P < 0.001), and a higher percentage of ADPKD children had significant microalbuminuria (> 15 mg/m2 per 24 h in boys and >23 mg/m2 per 24 h in girls) than their unaffected siblings (30% versus 10%, P < 0.05). Thirty percent of ADPKD children had albuminuria and 23% had overt proteinuria. For all ADPKD children, there was no correlation between proteinuria and hypertension. However, there was a significant correlation between urinary protein excretion and diastolic BP among children diagnosed after the first year of life (r = 0.23, P < 0.05). Therefore, proteinuria and albuminuria occur early in the course of ADPKD and may be markers of more severe renal disease.