Schmidt'S syndrome and severe hyponatremia: report of an unusual case and review of the related literature.

OBJECTIVE: To describe a rare case of profound hyponatremia in a male patient with autoimmune polyglandular syndrome type 2 (Schmidt's syndrome).
METHODS: We present the clinical and laboratory data in our patient and review the related published reports from the English language literature on the association of hyponatremia with Schmidt's syndrome.
RESULTS: A 31-year-old man presented to the emergency department because of nausea, anorexia, and weakness for 6 days. He was found to have severe hyponatremia (serum sodium concentration, 101 mEq/L) and mild hyperkalemia. Endocrine testing revealed the presence of Addison's disease and severe primary hypothyroidism, consistent with Schmidt's syndrome. The patient responded to treatment with volume and hormone replacement. An extensive literature search disclosed only one previously reported case (of a female patient) in which Schmidt's syndrome led to the development of a degree of hyponatremia as severe as that in our patient.
CONCLUSION: Concomitant occurrence of primary adrenal insufficiency and primary hypothyroidism can result in a greater degree of hyponatremia than would be expected from either disease alone. Likely explanations include the additive effects of primary hypothyroidism and adrenal failure in the development of hyponatremia and, possibly, in some patients exquisite renal sensitivity to hemodynamic changes and altered hormonal status.