Renal, cardiovascular and hormonal characteristics of young adults with autosomal dominant polycystic kidney disease

Abstract

We studied young adults with autosomal dominant polycystic kidney disease (ADPKD) to determine the characteristics that precede renal impairment. Nineteen affected (A) and 20 unaffected (U) offspring from families with ADPKD showed no significant differences in basal glomerular filtration rate (A: mean 97, SD 19; U: 100, SD 23 ml/min/1.73 m2) or renal functional reserve, but effective renal plasma flow was significantly lower in affected offspring (A: 532, SD 86; U: 605, SD 118 ml/min/1.73 m2, P < 0.01). Plasma renin activity [A: median 26 (95% CI: 15 to 37); U: 14 (11 to 27) μU/ml, P < 0.05, one-tailed test] and aldosterone [A: 2.5 (2.0 to 3.0), U: 1.0 (1.5 to 2.0) μg/100 ml, P < 0.04, one-tailed test] were increased in affected offspring despite the higher systolic blood pressure (A: mean 123, SD 5; U: 115, SD 3 mm Hg, P < 0.02) and significant expansion of total exchangeable sodium (A: 40.8, SD 2.3; U: 38.0, SD 3.5 mmol/kg, P < 0.01). The ouabain-sensitive component of red cell sodium efflux was less in affected offspring (A: 0.258; SD 0.040; U; 0.288, SD 0.042 hr-1, P < 0.04) and in both groups was correlated inversely with total exchangeable sodium. Echocardiography revealed no difference in left ventricular mass index nor prevalence of mitral valve prolapse. Potential cyst growth factors such as the glucocorticoids and somatomedin C were similar in both affected and unaffected groups. Reduced renal blood flow, renin system activation and increased body sodium precede the major clinical manifestations of ADPKD and may play a central role in the genesis of high blood pressure, and possibly also cyst growth, both of which are important determinants of the clinical course of ADPKD.