Endocrine Abstracts

59-year-old male, with a background of treated acromegaly, presented to endocrine clinic with new onset fatigue. He was diagnosed with acromegally 18 years prior to his presentation, and had a transphenoidal hypophysectomy followed by gamma-knife radiation. Post-surgery he developed partial anterior hypopituatrism (LH and FSH). He currently takes testosterone replacement. He is still receiving medical management with Somatuline. He developed hypothyroidism 16 years following his diagnosis and started on Levothyroxine supplementation. Almost 17 years from his initial presentation, during routine Endocrine clinic follow up, he reported fatigue. His morning bloods showed a cortisol of 96 nmol/l, together with an inappropriately normal/low ACTH of 15 ng/l confirming the diagnosis of secondary adrenal insufficiency. He was commenced on hydrocortisone therapy, following which his fatigue significantly improved. He is aware of sick day rules and remains under regular endocrine follow up. Hypothalamic-pituitary-axis function progressively declines following radiation therapy. This may be secondary to pituitary atrophy due to lack of stimulation or the delayed effects of direct radiation upon a hormonal axis. The average time to new onset pituitary deficiency has been reported as 29-96 months following radiotherapy. Growth hormone is most sensitive to the effects of radiation, followed by gonadotrophins, ACTH and TSH. Interestingly, this patients’ growth hormone secretion remains preserved. However, he developed ACTH deficiency after a staggering period of 17 years. Reports of late onset ACTH deficiency beyond 10 years are rare, perhaps owing to limited duration of follow up. This case demonstrates that patients who receive radiation therapy to the pituitary remain at risk of developing sequential pituitary deficiencies and endocrine follow up is essential for the rest of their lives. Endocrine deficiencies, including ACTH insufficiency, are associated with decreased quality of life and increased mortality; highlighting the importance of long term pituitary profiling and endocrine review.