Endocrine Abstracts

Hypothyroidism due to autoimmune aetiology can be associated with other autoimmune conditions such as Type 1 Diabetes Mellitus (T1DM) and primary adrenal insufficiency. Ruling out primary adrenal insufficiency is important in any patient with suspected autoimmune hypothyroidism.

Case: 43-year-old female complaining of general lethargy, sore throat, and neck pain. She was found to be hyponatraemic (Na+ 130) after being reviewed by the GP and was advised to attend Accident and Emergency. The patient was admitted with suspected septic shock and severe hyponatremia (Na 112). Her background includes PCOS, recently diagnosed hypothyroidism, and Acalculous Cholecystitis. In her first admission, she was found to be hypothyroid and was started on levothyroxine replacement. 6 weeks after starting treatment, she was admitted once more with severe lethargy, hyponatremia with low cortisol. She underwent further testing including a short synacthen test which showed a suboptimal response. Adrenal antibodies were positive. During her inpatient stay she was treated with IV hydrocortisone and then discharge home on oral hydrocortisone and fludrocortisone. She remains stable and her sodium level has normalized.

Discussion: Autoimmune polyendocrine syndrome II consists of autoimmune hypothyroidism, primary adrenal insufficiency, and/or T1DM (Smith & Gerritis 2019). Levothyroxine replacement augments liver corticosteroid metabolism, consequently precipitating an adrenal crisis in an individual with low cortisol (Betterle et al 2004). It is therefore important to keep a high index of suspicion of primary adrenal insufficiency in patients with autoimmune hypothyroidism. It is also important to ensure sufficient testing is carried out to allow for appropriate glucocorticoid replacement to be given prior to levothyroxine replacement in affected individuals.

Conclusion: Ruling out adrenal insufficiency prior to thyroxine replacement in a patient with hypothyroidism is vital given the co-existence of these autoimmune conditions. References1. Smith RK, Gerrits PM. A rare case of autoimmune polyglandular syndrome type 2 in a child with persistent fatigue. Glob Pediatr Health 2019;6:2333794X1984507–5.2. Betterle C, Lazzarotto F, Presotto F. Autoimmune polyglandular syndrome type 2: the tip of an iceberg? Clin Exp Immunol 2004;137:225–33.3. Fonseca V, Brown R, Hochhauser D, et al. Acute adrenal crisis precipitated by thyroxine. BMJ 1986;292:1185–6.4. Murray JS, Jayarajasingh R, Perros P. Lesson of the week: deterioration of symptoms after start of thyroid hormone replacement. BMJ 2001;323:332–3.5. Shaikh MG, Lewis P, Kirk JM. Thyroxine unmasks Addison’s disease. Acta Paediatr 2004;93:1663–5.