PLASMA AND URINARY ADH LEVELS IN PATIENTS WITH ESSENTIAL HYPERTENSION

Abstract

In order to investigate the regulatory system of release and excretion of ADH in essential hypertension, plasma and urinary ADH levels were determined in normal control subjects and patients with essential hypertension. Plasma ADH levels in 42 normal subjects and 53 patients with essential hypertension were 4.5 ± 0.18 pg/ml (mean ± SEM) and 4.0 ± 0.12 pg/ml, respectively, and a significant difference was found between the two groups. Urinary ADH excretion was 74.4 ± 9.5 ng/day (mean ±SEM) and 48.0 ± 8.2 ng/day in 15 normal subjects and in 17 patients, respectively, and it was significantly lower in the patient group. In 25 patients, plasma ADH levels were measured immediately upon admission and after a two week bed rest without medication following admission. A significantly negative correlation was observed between the change of mean blood pressure and plasma ADH levels. After two weeks, sodium restriction (Na : 35 mEq and K : 75 mEq, daily) was ordered for 1 week in 17 patients, and a significant elevation of plasma ADH levels and a remarkable lowering of the blood pressure was found. And there was also a significantly negative correlation between the change of mean blood pressure and plasma ADH levels. Since the linear regression line was steeper after sodium restriction than after a two week rest, the elevation of plasma ADH levels induced by sodium restriction may be considered to be affected not only by the blood pressure lowering but also by the decrease of plasma volume. From these results, it was suggested that the control of ADH release in essential hypertension was maintained normally, and that the baroreceptor might play an important role in regulation of ADH release under these conditions.