To appreciate the aldosterone secretion status in panhypopituitarism, the steroid response to stimulation was studied in a homogeneous group of 20 female patients presenting with global hypopituitarism. Specific effects of glucocorticoid and thyroid hormone deficiencies were also assessed by studying the same patients before and after cortisol (F) and cortisol plus thyroid hormone (F + T) substitution. The patients were submitted to two stimulation tests before and after each treatment: the orthostasis test (O-T) and the furosemide test (Furo-T). The results obtained in the 3 situations were compared, each patient serving as her own control. Comparison was also established with the results obtained in healthy women serving as control group. Basal plasma aldosterone levels in the untreated patients were not significantly different from those of the control group (5.43 \m=+-\0.51 vs 7.16 \m=+-\0.80 ng/100 ml, mean \m=+-\SEM). They were significantly lower after F (3.91 \ m=+-\ 0.42) and F + T substitution (3.31 \ m=+-\0.23) than those of untreated patients and controls. Response to both stimulations was blunted in the untreated patients (O-T: 14.10 \ m=+-\2.81; Furo-T: 9.78 \m=+-\1.35) as compared to the control group (O-T: 26.46 \m=+-\4.67; Furo-T: 23.96 \m=+-\ 3.30). F treatment did not improve the response to either tests, (O-T: 11.42 \ m=+-\2.55; Furo-T: 10.32 \m=+-\1.23).F + T treatment normalized the orthostasis response (20.83 \ m=+-\3.59) and increased the response to furosemide which remained, however, lower (15.28 \ m=+-\1.83) than in the control group. These results are in favour of a minor role of the pituitary in the regulation of aldosterone secretion. They emphasize the role of thyroid hormones which may act partly directly, partly through their effect on renin secretion.There is no general agreement on the effect of pituitary insufficiency on aldosterone secretion. Most published data indicate a normal basal secre¬ tion but different responses to various stimuli (Williams et al. 1971;Lefebvre et al. 1979; Me Caá et al. 1981; Birkhäuser et al. 1981). These differ¬ ences can be related to the small number of patients investigated in each series, their hetero¬ geneity with respect to sex, age, aetiology of pituitary insufficiency, degree of pituitary failure, extent of hormonal substitution and protocol of study. Therefore it is difficult to draw any firm conclusion from these studies. To circumvent some of these impedimenta, we have studied a homogeneous group of 20 female patients of child-bearing age, affected by post-partum pitui¬ tary necrosis with global hypopituitarism. In a previous paper (Bakiri et al. 1983) we have stud¬ ied their renin-angiotensin system. We report now their aldosterone response, under the same stimulatory conditions i.e. an orthostasis test and an acute sodium depletion. In order to define a specific role, if any, of glucocorticoid and/or thy¬ roid hormone deficiency, the same patients have been assessed before and after substitutive treat¬ ment with cortisol (F) alone an...