Endocrine Abstracts

Introduction: A 40-year-old woman, despite previously well controlled Hypothyroidism and Addison’s disease, presented with adrenal crisis due to extremely rare cause.

Case Report: In 2002, age 31 years, she presented with symptoms of anorexia, weight loss and postural hypotension. She was subsequently diagnosed to have Addison’s disease and primary hypothyroidism (confirmed with positive adrenal and thyroid peroxidase antibody). She was started on Hydrocortisone, Fludrocortisone and 5 days later Levothyroxine was initiated. She was regularly reviewed in endocrinology clinic.

Nine years later, she presented with 2 month history of excessive sweatiness, restlessness, heat intolerance, dizziness, weight loss and increased skin pigmentation despite doubling the dose of Hydrocortisone (20 mg am and 10 mg pm) and taking regular Fludrocortisone and Levothyroxine.

On examination, she had tachycardia (heart rate – 123 bpm), marked postural hypotension, increased tremulousness of outstretched hands and small diffuse goitre.

Investigation confirmed biochemical thyrotoxicosis; Free T4 – 47 (ref 11–23 pmol/l), FT3 – 25.9 (4.1–7.9 pmol/l), TSH < 0.02 (0.3–5.5 mU/l), Cortisol −18 nmol/l, Adjusted Calcium 2.50 mmol/l and TPO Antibody > 1300 (ref <60 IU/ml). Her TSH receptor antibodies were positive.

Levothyroxine was stopped and antithyroid medication was initiated. Gradually her TFT normalised.

Conclusions: This case highlights few important points:

1. When patient with Hashimoto’s hypothyroidism present with hyperthyroidism, over-replacement with Levothyroxine is the likely cause, but possibility of endogenous hyperthyroidism should be considered.

2. Transformation of Hashimoto’s hypothyroidism to Graves’ hyperthyroidism is extremely rare, but does occur. This is due to presence of different types of TSH Receptor Antibodies which recognise different epitopes of TSH receptors and modify the patients’ thyroid functions, resulting in hyperthyroidism or hypothyroidism.

3. Development of thyrotoxicosis in a patient with otherwise well controlled Addison’s disease can result in hypoadrenal crisis as thyroid hormones accelerate glucocorticoid turnover and increase glucocorticoid requirement.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.