Isolated adrenocorticotropic hormone deficiency (IAD) is considered to be a rare disease. Due to the nonspecific clinical presentation, precise data on the prevalence and incidence are lacking. In this systematic review, we aimed to analyse the clinical characteristics, association with autoimmune diseases, and management of acquired idiopathic IAD cases. A structured search was conducted after developing a search strategy combining terms for acquired (idiopathic) IAD. Articles describing an adult case with a diagnosis of ACTH deficiency using dynamic testing, no deficiency of other pituitary axes, and MRI of the brain/pituitary protocolled as normal, were included. Exclusion criteria were cases describing congenital IAD, cases with another aetiology for IAD, and articles where full text was not available. In total 42 articles were included, consisting of 85 cases of acquired idiopathic IAD. Distribution by sex was approximately equal (F:M; 47:38). Lethargy was the most common presenting symptom (38%), followed by weight loss (25%), anorexia (22%), and myalgia/arthralgia (12%). Eight cases (9.5%) presented with an Addison crisis. 31% of cases had an autoimmune disease at diagnosis of which Hashimoto hypothyroidism was the most frequent. Data about follow-up was scarce; dynamic testing was repeated in 4 cases of which 2 showed recovery of the adrenal axis. We report the largest case series of acquired idiopathic IAD to date. Our systematic review highlights the lack of a clear definition and diagnostic work-up. Based on the findings in this review a proposition is made for a flowchart to diagnose acquired idiopathic IAD.

OBJECTIVE: Isolated ACTH deficiency (IAD) is defined as an impaired secretion of ACTH from the pituitary gland without any other anterior pituitary hormonal deficits. The idiopathic form of IAD has been described mainly in adults and is thought to be caused by an autoimmune mechanism.
METHODS: Herein, we present an 11-year-old _prepubertal previously healthy boy, who suffered a severe hypoglycemic episode short after the initiation of thyroxine for autoimmune thyroiditis and was finally diagnosed with secondary adrenal failure due to idiopathic IAD, after all other etiologies were excluded, thought an extensive diagnostic work-up.
CONCLUSIONS: Idiopathic IAD is a rare entity of adrenal insufficiency in pediatrics that should be considered as an etiology of secondary adrenal failure in children, when clinical signs of glucocorticoid deficiency are present and other causes are excluded.

Idiopathic Isolated ATCH deficiency (IIAD) is a rare cause of secondary adrenal insufficiency. As the condition is rare, and the diagnostic criteria ill-defined, there are few good clinical descriptions in the literature. We have described presenting features, autoimmune associations, natural history and responses to CRF, in a large case series of patients presenting with IIAD.
This is a retrospective case note analysis with data derived from the recently commenced National Pituitary Database of Ireland.
Twenty-three patients with isolated ACTH deficiency were identified. A thorough chart and biochemistry review was performed.
Twenty-three patients were examined (18 women and 5 men). Age at presentation ranged from 17 to 88 years, (median 48 years). Most patients complained of fatigue; 9 patients presented with hyponatraemia, 13 had autoimmune illnesses (primary hypothyroidism, n = 9). CRF stimulation testing was available in 12 of the 23 patients, 5 of whom demonstrated a rise in plasma ACTH concentrations, indicating hypothalamic, rather than pituitary aetiology. Two patients recovered ACTH secretion, and 2 patients progressed to have other pituitary hormone deficiencies.
IIAD typically presents with insidious symptoms. Euvolaemic hyponatraemia is common at diagnosis. It is associated with autoimmune diseases, particularly primary hypothyroidism. As two patients recovered ACTH secretion, and two progressed to other pituitary hormone deficits, repeat pituitary testing should be considered, to identify recovery of function, or progression to other hormone deficits.