Endocrine Abstracts

Idiopathic Isolated ATCH deficiency (IIAD) is a rare cause of secondary adrenal insufficiency characterised by ACTH deficiency with otherwise intact pituitary function. Our objective was to describe the presentation, the autoimmune associations and diagnostic findings observed in IIAD. We present a case series of 19 cases of idiopathic Isolated ACTH deficiency which were identified from the National Pituitary Register in Ireland. A chart and biochemical review was performed to identify the presentation, clinical features, diagnostic criteria and associated diseases of people with IIAD. All patients had normal pituitary MRI imaging, (one patient refused, however he had a normal CT brain) and other causes for ACTH deficiency such as medication or traumatic brain injury were excluded. 19 patients were identified as meeting criteria (15 women and 4 men). The age at presentation ranged from 21 to 88 years, with a median age of 52 years. The majority of patients complained of fatigue and lethargy; however five patients presented with hyponatraemia. 10 of the 19 patients had autoimmune illnesses; hypothyroidism was the most common autoimmune disease with eight patients suffering primary hypothyroidism. CRH stimulation testing was available in 6 of the 19 patients, five of these patients had a rise in ACTH with CRH administration, indicating possible hypothalamic involvement. Two patients had complete recovery of their HPA axis when repeat testing was performed. IIAD is a rare, poorly defined disorder that typically presents with insidious symptoms but can present with severe hyponatraemia. It is associated with autoimmune diseases, in particular primary hypothyroidism. Two patients in this case series had complete recovery of their HPA axis, therefore repeat testing should be performed at intervals.