Endocrine Abstracts

A 22 years old woman presented with a few days history of nausea, vomiting and general lethargy. She was not on any treatment except the oral contraceptive pill (OCP). She was apyrexial, tachycardic at 140/min with a regular pulse and her blood pressure was 110/70. She was not pigmented. Her plasma sodium was 131 mmol/l, with normal potassium, creatinine and urea. Her arterial blood gas analysis showed a pH of 7.22 and bicarbonate of 12mmol/L. Her TFTs showed a thyrotoxic picture with fT4 of 28.6 pmol/L, fT3 of 8.0 pmol/L and a suppressed TSH. Initial random blood glucose was 2.2 mmol/L. Serum lactate was not elevated and Salicylate was not detected in the blood. A random cortisol and ACTH were sent off. She was rehydrated with IV Saline and her thyrotoxicosis was treated with Propranolol resulting in partial symptomatic improvement with some improvement in her pulse rate. Her random plasma cortisol was low at 34 nmol/L and her plasma ACTH was undetectable. She was started on hydrocortisone with total resolution of her symptoms and normalisation of plasma bicarbonate levels. Subsequently, a short synacthen test (250 mcg) showed a peak cortisol at 47nmol/L, while cortisol levels peaked at 505nmol/L after a long synacthen test. A Glucagon stimulation test revealed a normal growth hormone response but no cortisol response (peak cortisol <20 nmol/L). Her prolactin was 356 mIU/L. MRI of the pituitary was normal. Subsequently, she developed transient hypothyroidism, but her TFTs normalised 8 weeks after the initial presentation, consistent with thyroiditis. We believe that the acute metabolic acidosis was due to Addisonian crisis (isolated ACTH deficiency), which was precipitated by thyrotoxicosis associated with thyroiditis. She remains well on hydrocortisone 10 months after the initial presentation and her periods are regular after stopping her OCP.