Endocrine Abstracts

This 46 year old lady with no significant past medical history was referred urgently to the Endocrine Investigation Unit with a 9 month history of increasing lethargy and gradual weight loss of around 5 kg. Two months prior, she had been diagnosed with subclinical hypothyroidism and after commencing Levothyroxine, quickly lost another 5 kg in weight over a period of 6 weeks and had postural dizziness with systolic BP readings between 80 and 90 mmHg. She was having a normal menstrual cycle. She works as a Vet. Her father has Type 1 Diabetes and Coeliac Disease. On examination, she felt that her skin was more tanned than she would expect for the winter. Her dentist had commented on slight gum pigmentation. There were no pigmented scars. Blood tests in primary care showed sodium 129 mmol/l, potassium 4.9 mmol/l, fasting glucose 5.1 mmol/l and an undetectable 9am cortisol at <28 nmol/l. Thyroid function two months prior showed TSH 10.25mU/l (0.35-4.94 mU/l) and free T4 8.1pmol/l (8-19.1pmol/l). After commencing Hydrocortisone 10mg on waking and 10mg at 5pm, her energy levels and dizziness improved dramatically. ACTH (on Hydrocortisone) was 84ng/l (7-56ng/l) and adrenal antibodies were positive. She was informed of her diagnosis of primary adrenal insufficiency, Addison”s disease. She was provided with information on the condition and understands the steroid sick day rules. She was commenced on Fludrocortisone 50 mg daily and her Hydrocortisone dose was adjusted to 10mg on waking and 5mg at 5pm, with the suggestion that she may require an additional 5mg on more stressful or active days. She received preliminary steroid education with the Endocrine Specialist Nurse.

Discussion: This case illustrates some important learning points 1: Elevated thyroid stimulating hormone without signs of primary hypothyroidism can be a feature of adrenal insufficiency and may improve after glucocorticoid replacement. She had weight loss, where weight gain is more classically associated with hypothyroidism. 2: Although adrenal insufficiency was not considered in her case initially - it is important that it is confirmed or ruled out if suspected, before treatment of hypothyroidism, to reduce risk of precipitating an adrenal crisis. Her symptoms were likely exacerbated after commencing Levothyroxine due to increased cortisol clearance and increased metabolic rate. 3: The presence of related autoimmune conditions should be considered and in this lady”s case it will be important to reassess thyroid antibody status and need for continued thyroid replacement once her adrenal insufficiency has been addressed.