A study of plasma vasopressin in patients undergoing chronic hemodialysis.

Plasma vasopressin (VP) was determined in 28 patients with chronic renal failure undergoing hemodialysis. Plasma VP levels were significantly higher in the patients than in the normal subjects. It was also observed that plasma VP levels did not fall significantly despite a marked decrease of effective plasma osmolality following hemodialysis, and that no correlation was obtained between the plasma VP levels and effective plasma osmolality, both before and after hemodialysis. By analyzing the changes in blood volume and blood pressure in addition to plasma osmolality in each case, a dysfunction of VP release in response to osmotic stimulus was found in 5 out of 28 patients.