PLASMA-CONCENTRATION OF ANTI-DIURETIC HORMONE IN PATIENTS WITH CHRONIC RENAL-INSUFFICIENCY ON MAINTENANCE DIALYSIS

Radioimmunoassay of plasma arginine-vasopressin (AVP) in regularly dialyzed patients with chronic renal insufficiency revealed a parallel increase of AVP and plasma osmolality (P(Osm)) before dialysis (4.16 ± 0.36 pg/ml and 312.6 ± 1.80 mOsm/l) and their parallel decline to the normal range (1.93 ± 0.27 pg/ml and 292.0 ± 1.27 mOsm/l) during dialysis. Plasma AVP correlated with P(Osm) before and after dialysis (r=0.611 and 0.453, p<0.01 and <0.05 respectively). The increase of AVP before dialysis was lower than would correspond to the rise of P(Osm) and lower than that recorded in healthy subjects during dehydration. Statistical correlation between plasma AVP and indicators of body fluid volume changes between or during dialyses were not proved. We found statistical correlation between the mean blood pressure and AVP before dialysis (r=0.468, p<0.05). These findings suggest that in chronic renal insufficiency changes of P(Osm) remain the primary regulating factor of AVP secretion. The expansion of extracellular fluid volume has probably only a modifying effect. It remains to be elucidated whether the revealed statistical relationship between the mean blood pressure and AVP before dialysis plays also a pathogenetic role in the development of hypertension in chronic renal insufficiency.