Endocrine Abstracts

Introduction: Graves’ thyrotoxicosis and Addison’s disease are disorders with a strong auto-immune basis. Primary hypothyroidism and Addison’s disease are recognised components of polyglandular autoimmune syndrome type II (PGA-II). Despite its autoimmune etiology, Graves disease is not commonly associated with PGA-II. We present a case of a patient with newly diagnosed Graves’ disease presenting in incipient adrenal crisis due to unrecognized Addison’s disease.

Case report: A 35-year-old gentleman presented with headache, paraesthesia, heat intolerance, and weight loss associated with severe fatigue, nausea and vomiting. Graves’ thyrotoxicosis was suspected and confirmed biochemically (TSH <0.01 mU/l, FT₄ 30.7 pmol/l, FT₃ 8.6 pmol/l). He was treated with Carbimazole 40 mg once daily for a few weeks without any symptomatic improvement. He was referred to our unit with progressive weight loss, dizziness and fatigue. On re-assessment he looked unwell and was deeply tanned and hypotensive. Addison’s disease co-presenting with Graves’ disease was suspected. ACTH stimulation with tetracosactide (Syncathen) showed no incremental cortisol response (baseline cortisol 48 nmol/l) and elevated serum ACTH (679 ng/l) confirmed primary adrenal insufficiency. Graves’ thyrotoxicosis was treated with Carbimazole. Catabolic symptoms resolved completely with glucocorticoid and mineralocorticoid replacement therapy.

Discussion: Thyroid dysfunction and Addison’s disease are recognised components of polyglandular autoimmune syndrome type II (Schmidt syndrome). Primary hypothyroidism is the norm and Graves’ thyrotoxicosis is very rarely recognized as part of the syndrome. It is well recognized that occult Addison’s disease should be suspected in patients who fail to improve symptomatically after commencing levothyroxine for primary hypothyroidism. This case highlights the fact that patients presenting with Graves’ disease and Addison’s simultaneously are at risk of incipient adrenal crisis. A high index of suspicion remains the cornerstone of diagnosis.