Endocrine Abstracts

Introduction: Isolated acquired ACTH deficiency is rare; it may be due to hypophysitis and association with other autoimmune diseases was reported.

Case report: E.L, female, aged 34, was diagnosed with primary autoimmune hypothyroidism and premature ovarian failure; levothyroxine and estroprogestins were administered. Suddenly, the patient developed vomiting, shivers without fever and soon coma installed, with tonic-clonic seizures. There was no history of recent pregnancy or traumatic injury. Biochemical data revealed severe hyponatremia (<100 mmol/l) with normokalemia (4.2 mmol/l); thyroid function was normal on L-T₄ therapy (TSH=1.91 mIU/l, FT₄=1.2 ng/dl). Adrenal deficiency was suspected. I.v. dexametasone 24 mg/day and saline were administered, with progressive, slow normalisation of natremia, followed by remission of coma and seizures. Further tests supported isolated ACTH deficiency: decreased plasma 0800 h cortisol (2.6 μg/dl), with low normal ACTH levels (8.2 pg/ml). Short Synacthen test (250 μg) showed inadequate cortisol stimulation (9.9 μg/dl at 30 min, 13.6 μg/dl at 60 min) and prolonged ACTH stimulation test (3 days) revealed adequate cortisol stimulation at 24 h (39.8 μg/dl), 48 h (31.1 μg/dl) and 72 h (43 μg/dl). Insulin tolerance test could not be performed due recent history of seizures, but insufficient response to glucagon test (maximum cortisol levels=10.9 μg/dl) supported the diagnosis. All other pituitary hormones were in normal range. Cerebral and pituitary MRI, adrenal CT scans were normal. Hydrocortisone 20 mg/day was administered, with maintenance of normal natremia and kalemia. Low sodium levels were reported in 28% of cases with isolated ACTH deficiency, but hyponatremic coma was very seldom reported.

Conclusion: This case emphasis the importance of considering isolated central adrenal insufficiency when encountering hyponatremic coma.