Rare Hormone Deficiency Identified After Repeated Low Blood Sugar Episodes

Isolated Adrenocorticotropic Hormone (ACTH) deficiency (IAD) is an uncommon endocrine disorder characterized by the pituitary gland's inability to produce sufficient ACTH, leading to secondary adrenal insufficiency and inadequate cortisol production. While typically developing gradually, sudden onset IAD can present with atypical and non-specific symptoms, making timely diagnosis particularly challenging. This case report uniquely highlights the diagnostic journey of IAD when its primary manifestation is recurrent, severe hypoglycemic attacks, underscoring the need for heightened clinical suspicion in such unusual presentations.

Initial emergency presentations consistently revealed profoundly low blood glucose levels, frequently plummeting below 40 mg/dL, necessitating immediate medical intervention. Basal morning cortisol levels were found to be consistently suppressed, averaging around 1.5 µg/dL (significantly below the normal range of 5-25 µg/dL), while circulating ACTH levels were inappropriately low or even undetectable, often less than 5 pg/mL (normal range 6-50 pg/mL), despite the severe cortisol deficiency. Pituitary magnetic resonance imaging (MRI) showed no structural abnormalities, effectively ruling out a tumor as the cause. > The definitive diagnosis was established via the CRH stimulation test, which demonstrated a markedly blunted cortisol response, with peak levels failing to rise above 5 µg/dL, unequivocally confirming secondary adrenal insufficiency due to isolated ACTH deficiency. Following the diagnosis, the patient was immediately started on hydrocortisone replacement therapy at a physiological dose of 15 mg/day (administered as 10 mg in the morning and 5 mg in the evening). This intervention led to a 100% resolution of all hypoglycemic episodes within one week, with sustained glycemic stability observed over a six-month follow-up period.