Nocturnal diuresis in panhypopituitarism.
Although impaired water diuresis in adrenocortical insufficiency is well-known, little attention has been paid to the diuretic pattern at night. In two cases of panhypopituitarism, the nocturnal diuretic pattern was found to be quite different from that in the morning, and marked diuresis did occur after water loading at night, without any significant change of serum cortisol which remained at a low level throughout the day. At the antidiuretic stage in the morning, urine osmolality continued to rise gradually, in spite of the water loading, to the level of 666 mOsm/liter. At the water restriction test, the urine was concentrated only to the same level of 600-700mOsm/liter. At the ascending stage of urine osmolality, exogenously injected pitressin showed little antidiuretic effect, although the kidney was able concentrate urine to the higher level later. In the morning, 3 liters of 5% glucose infusion failed to produce a marked diuresis in spite of extreme plasma dilution and expansion. Furosemide immediately induced diuresis even in the morning and the kidney recovered its ability to respond to pitressin. Glucocorticoid also improved the diuretic pattern in the morning, but a latent period of about 2 hr was always observed before the appearance of the effect. What happened during this latent period was unclear, but it was interesting to note that a mechanism similar to that which induces diuretic response seemed to occur without glucocorticoid at night.