Heparin elimination in uraemic patients on Haemodialysis

Heparin (100 U/kg bodyweight) was administered as single i.v. injections, and heparin concentration in plasma determined by polybrene titration. Mean concentration half-life was 74.7 min in the normal group (n = 6), 118.6 min in the nephrectomized patients (n = 5), and 97.8 min in the other uraemic patients (n = 6). The differences between the mean values for the normals and for the 2 patient groups were statistically significant (p is less than 0.001 and p approximately 0.2 respectively). Mean anticoagulant half-life (based on thrombin clotting time) was 64.3, 75.8 and 62.7 min in the 3 groups. The differences between heparin concentration half-life and anticoagulant half-life in the 3 groups were statistically significant. These differences may be partly explained by a significant fall in heparin cofactor activity after injection of heparin. There was a strong positive individual correlation between heparin concentration half-life and anticoagulant half-life in the patients (r = 0.94), but not in the normal group (r = 0.31). There was a strong negative individual correlation between heparin tolerance and heparin concentration half-life in the patients (r = -0.84), but no correlation in the normal group. It is concluded that severely impaired renal function has a significant, but moderate influence on heparin elimination.