Summary
Heparin neutralizing activity (HNA) was increased in plasma of patients with end-stage
renal disease treated by maintenance haemodialysis. It was not raised in non-dialyzed
patients with chronic renal failure, nor in patients with normal renal function who
had been exposed to the extracorporeal circulation of the heart-lung bypass 48–72
hr before testing. It is postulated that the trauma of extracorporeal circulation
causes platelets to release HNA which is not cleared by the dialysis membranes of
the artificial kidney but is by the human kidney. This may have therapeutic implications
for heparin dosage schedules during haemodialysis.
