Endocrine Abstracts

Background and Aims: Thyroid hormone can accelerate glucocorticoid turnover and there have been cases of adrenocortical insufficiency reported after radioactive iodine treatment. However, the patient presented here did not have any such precipitant nor any underlying adrenal disease, and her adrenal insufficiency resolved after treatment of thyrotoxicosis.

Methods: A case of a 45-year-old lady with Graves’ disease is presented, who developed hypoadrenalism at the time of her diagnosis which settled with the treatment of underlying thyrotoxicosis.

Results: A 45-year-old lady presented with nausea, light-headedness, and sweats which started 3 weeks after her COVID vaccine booster. Her symptoms included syncopal symptoms, muscle weakness, nausea, vague abdominal pain, constipation, dry mouth, intermittent headache, legs feeling shaky, weight loss, and appetite loss. Her blood pressure at the time of presentation was 107/70 with no significant postural drop. She was normoglycemic with no neck lumps and an otherwise normal physical examination. Her initial blood tests showed a free T4 level of 82.9 pmol/l with a TSH of <0.01 mU/l. Her morning cortisol level was 218nmol/l, and short synacthen test showed a rise from 178nmol/l to 371 nmol/l. She was commenced on carbimazole 1 mg daily and hydrocortisone 1 mg BD. Her symptoms improved with treatment and her dose of Carbimazole has gradually been reduced to 1 mg daily over a year. Three months after the initial presentation when her free T4 level dropped to 18.1 pmol/l, she had a repeat short synacthen test which showed a rise of cortisol from 342nmol/l to 546nmol/l. The patient was advised to discontinue hydrocortisone, however, due to her concerns about symptoms it was continued for another 3 months after which a repeat SST was carried out which again showed a satisfactory response, and hydrocortisone was withdrawn. Her adrenal antibodies were checked which were negative while the thyroid receptor antibody was positive at 27U/l\. She remains well on 1 mg of carbimazole a year after her initial presentation and has been off steroids for 6 months.

Conclusions: It is important to be aware of the possibility of adrenal insufficiency in patients with autoimmune hyperthyroidism, which can be a concomitant presentation of autoimmune adrenal insufficiency but in rare cases can be due to increased clearance of cortisol due to an excess of thyroid hormone.