Estimation of Plasma Arginine Vasopressin Concentration Using Thirst Perception and Plasma Osmolality Values

Abstract

Summary: In human, thirst and antidiuretic hormone (ADH) are controlled by similar sensitive osmoregulatory mechanisms such that above a certain osmotic threshold (280-288 mOsm/kg H₂0) there is a linear relationship between the increase in plasma osmolality and increase in ADH and thirst. The purpose of this study was to estimate plasma arginine vasopressin (P_AVP) using thirst perception (TP) and plasma osmolality (P_OSM) values before and at 60 minutes in control or euhydrate (group A, 0.0 ml/kg body weight of distilled water), hydrated (group B, 7.1ml/kg body weight of distilled water) and dehydrated (group C, 0.0 ml/kg body weight of distilled water) subjects. A total of twenty five (25) subjects between the ages of 18 and 30 years were used for the study. Calculated P_OSM and TP values were used to estimate the P_AVP concentration. Data were presented as Mean ± SEM. Analyses of results were done using ANOVA and Student t-test. The estimated values of P_AVP using TP and P_OSM respectively at baseline levels were similar in euhydrate (2.22+2.00 vs 2.40+2.10 pg/ml), hydrate (2.22+1.34 vs 2.40+1.72 pg/ml) and in dehydrate (7.05+1.70 vs 6.92+1.94 pg/ml). Sixty minutes later, the values remained similar in euhydrate (3.29+2.40 vs 4.16+2.10 pg/ml), hydrate (1.92+1.60 vs 1.79+1.25 pg/ml) and in dehydrate (8.40+1.40 vs 9.20+1.50 pg/ml). The results show that there was a positive relationship between P_AVP calculated from TP and P_OSM values. We therefore concluded that plasma arginine vasopressin concentration may be estimated using thirst perception and/or plasma osmolality values. Estimation of P_AVP using plasma osmolar changes affected by glucose and urea may be inappropriate.

Keywords: Arginine vasopressin, Thirst perception, Plasma Osmolality.