Endocrine Abstracts

A 52-year-old, previously well Indian lady was admitted in May 2008 with pneumonia. Concurrently, she was diagnosed with diabetes mellitus (blood glucose 20 mmol/l). Her BMI was 19 kg/m² and she was initially commenced onto sulphonylurea therapy. She had a further admission in July 2008 with dizzy episodes, falls, postural hypotension (systolic postural drop 75 mmHg) and erratic blood glucose levels (range 1.1–30 mmol/l). Blood ketones were 3.6 mmol/l without acidosis.

C-peptide (702 pmol/l) was present and islet cell antibodies were negative, but anti-GAD antibodies were positive. The diagnosis was modified to Latent Autoimmune Diabetes in Adults (LADA) and insulin was initiated. An initial short synacthen testing (SST) revealed low basal cortisol but adequate rise post synacthen. Basal ACTH and plasma renin activity were not elevated (8.3 ng/l and 1.17 nmol/l per h respectively), although adrenal antibodies were positive. Fludrocortisone therapy led to some clinical improvement. Further testing revealed subclinical hypothyroidism (free T₄ 14 pmol/l, thyroid stimulating hormone 13 mu/l) with strongly positive thyroid peroxidise antibodies (>910 u/ml). She was commenced on levothyroxine. During further admissions with unresolving dizziness and nausea, further SSTs revealed an increasingly suboptimal response to synacthen. In summary, we present a case of autoimmune polyglandular syndrome type 2 in development, characterised by autoimmune Addison’s disease in combination with autoimmune hypothyroidism and autoimmune diabetes. It is particularly interesting to observe the progression of endocrine hypofunction over time. Furthermore, we hypothesise that the absence of expected rise in plasma renin activity is due to diabetic hyporeninaemia secondary to renal juxtaglomerular glycosylation.