Introduction:
Thyroid hormone is known to accelerate glucocorticoid turnover. In a thyrotoxic state, individuals with adrenal insufficiency are unable to increase endogenous cortisol production to compensate for increased turnover, placing them at risk for symptoms of glucocorticoid deficiency and adrenal crisis. In patients with salt-wasting congenital adrenal hyperplasia (SW-CAH), hyperandrogenemia is a measurable reflection of relative glucocorticoid insufficiency.
Case presentation:
A 12-year-old girl with SW-CAH reported 3 recent episodes of vomiting without diarrhea, and accompanying tachycardia, responsive to stress dose steroids. In the previous 9 months, she unintentionally lost 2.6 kg. She had tachycardia and new thyromegaly. Labs showed suppressed TSH, elevated free T4 and total T3, and elevated thyroid stimulating immunoglobulin (TSI) consistent with Graves' disease. Adrenal androgens were markedly elevated. Maintenance hydrocortisone dose was 25 mg/m2/day and was not changed. Methimazole was initiated. Four weeks later, free T4 and adrenal androgens normalized. She had no further vomiting episodes.
Conclusions:
Thyrotoxicosis must be included in the differential diagnosis of individuals with SW-CAH who present with episodes concerning for adrenal crises, escalating hydrocortisone requirements, and/or inadequate suppression of adrenal hormones.