Vasopressin response in haemodialysis patients

Ten patients underwent repeated haemodialysis under circumstances of manipulated change in plasma osmolaity and blood volume. Basal plasma arginine vasopressin (AVP) levels were significantly higher than in normal controls, but no linear correlation between basal plasma osmolality and AVP levels was found. In 38 of 44 studies there was an appropriate response of AVP to change in plasma osmolality or blood volume. We conclude that the quantitative response of AVP in dialysis patients is not linear and differs markedly as compared to normals. Changes in blood volume may play a more dominant role in the control of AVP release.