A case of isolated ACTH deficiency with hyporeninemic hypoaldosteronism.

A case of isolated ACTH deficiency with hyporeninemic hypoaldosteronism, presenting severe hyponatremia, is described. A 57-year-old man complaining of nausea, vomiting and fatigability was admitted to our hospital because of hyponatremia (114 mEq/I). The low levels of serum cortisol and urinary 17-OHCS suggested glucocorticoid deficiency, and that the glucocorticoid deficiency was due to isolated ACTH deficiency was confirmed by a continuous ACTH loading test and pituitary gland stimulation tests. Although the low level of serum sodium was normalized after the administration of cortisone acetate (50 mg/day) combined with an increase in oral salt intake, urinary sodium loss persisted by the results of hypertonic saline infusion test. Treatment led to improvement of impairment of water diuresis due to hypersecretion of ADH. Hyporeninemic hypoaldosteronism persisted after treatment. We have shown that severe hyponatremia that occurs with combined deficiency of glucocorticoids and mineralocorticoids can be corrected with high salt intake and glucocorticoid replacement without correcting mineralocorticoid deficiency.