Radioimmunoassay of urinary antidiuretic hormone in man: response to water load and dehydration in normal subjects.

Abstract

A simple, efficient procedure for extracting and concentrating antidiuretic hormone (ADH) from urine has been coupled with a specific radioimmunoassay for ADH in order to quantitate urinary excretion of the hormone. Normal human subjects under conditions of normal activity and random hydration excreted a mean value of 28.9 mU ADH/24 hr, with excretion in 70% of the subjects ranging between 11– 30 mU/24 hr. No difference in hormone excretion was found in urine collected during waking hr and during sleep. In response to oral water loading, plasma osmolality fell to 269–283 mOsm/kg and urinary ADH excretion became undetectable during the peak of the diuresis in 19 of 22 subjects. Following 14 hr of fluid deprivation, plasma osmolality rose to a mean of 290.6 mOsm/kg and urinary ADH excretion rose from 1.00 ± 0.19 mU/hr to 2.74 ± 0.53 mU/hr. ADH excretion can be readily quantitated in normal subjects and appears to respond to alterations in plasma osmolality which affect ADH release from the posterior pituita...