Decreased sensitivity to heparin in vitro in steroid-responsive nephrotic syndrome

The in vitro heparin sensitivity of 18 nephrotic children was compared with that of 10 normal children and 13 children with other renal diseases. The influence of age on the heparin sensitivity of 52 normal subjects (aged 12 to 85 years) was also studied. The heparin sensitivity was calculated from the dose-response curve obtained when increasing amounts of heparin were added to plasma and the kaolin partial thromboplastin time (KPTT) was measured. There was a significantly-reduced heparin sensitivity in nephrotic children compared to the control children and a progressive decline in heparin sensitivity with age. In the nephrotic syndrome heparin-sensitivity correlated with albumin and triglyceride concentrations but not with antithrombin III, platelet factor 4, cholesterol, fibrinogen, heparin cofactor II or histidine-rich glycoprotein. Addition of exogenous albumin did not restore the heparin sensitivity of nephrotic plasma. Four patients with Type II hyperlipidemia had a normal sensitivity to heparin. The decreased sensitivity to heparin thus does not appear to be a consequence of the nephrotic state, and may be a reflection of an underlying disturbance of charged macromolecules in steroid-responsive nephrotic syndrome.