ROLE OF ANTIDIURETIC-HORMONE IN IMPAIRED WATER-EXCRETION OF PATIENTS WITH CONGESTIVE HEART-FAILURE

Plasma antidiuretic hormone (ADH), PRA [plasma renin activity] plasma osmolality, and the parameters of renal water excretion were measured after overnight dehydration and for 5 h after an oral load in 14 patients with congestive heart failure (CHF) treated with diuretics (group 1), 8 hypertensive patients without CHF also treated with diuretics (group 2), and 11 patients with coronary artery disease but without CHF who were not treated with diuretics (group 3). Under basal conditions, mean plasma osmolality was lower in group 1 than in group 3, but was not different in group 1 and 2. Mean plasma ADH was higher in group 1 than in group 3. In response to the water load, plasma osmolality and plasma ADH levels decreased in the 3 groups. ADH levels remained significantly greater in group 1 than in groups 2 and 3 from 2-4 h after the H2O load despite more marked hypoosomolality in group 1 compared with that in either of the 2 control groups. Plasma ADH was significantly correlated with plasma osmolality only in the 2 control groups. Mean PRA was greater in patients with CHF and patients without CHF treated with diuretics than in untreated patients. Cumulative water excretion was lower in patients with CHF than in patients in the 2 control groups from 2-5 h after the water load. At 5 h, the mean percentage excretion of the ingested loads was 56.8%, 90.7%, and 91.2% in the patients of groups 1, 2, and 3 respectively. Free water clearance was lower and minimal urinary osmolality was greater in the patients with CHF than in those in the 2 control groups. Two patients with CHF, who excreted more than 75% of the water load, also had low plasma basal ADH levels. Patients with CHF have an inappropriate response of plasma ADH to a marked fall in plasma osmolality. This disorder is not due to the diuretic therapy, since hypertensive patients treated with diuretics behaved similarly to untreated patients without CHF. The reasons for this inappropriate response of plasma ADH during a water load in patients with CHF are probably multifactorial.