Endocrine Abstracts

Background: Isolated adrenocorticotrophic hormone (ACTH) deficiency (IAD) is a rare cause of secondary adrenal insufficiency. Its symptoms can overlap with post-viral or long-COVID fatigue, making recognition challenging.

Case Presentation: A 35-year-old man was referred to endocrinology clinic for persistent and worsening fatigue and mild cognitive impairment following COVID infection in 2021, during which he was unwell for 6 days but did not require hospital admission or oxygen. Initial testing showed morning cortisol 166 nmol/l, with normal electrolytes, glucose, and inflammatory markers. He denied exogenous steroid use, trauma, infection, or drug misuse. He was not taking regular medications apart from prior finasteride use and topical dihydrotestosterone-blocking shampoo for hair loss. Repeat assessments demonstrated persistently reduced cortisol (108 nmol/l) and low ACTH (< 6 ng/l) with other pituitary axes stable. MRI pituitary with contrast was normal. The findings were consistent with isolated ACTH deficiency. He responded well to low-dose prednisolone, with marked symptomatic improvement.

Conclusion: IAD is a rare disorder. Post-COVID IAD cases have been reported only sporadically. In this case, the temporal association may suggest a possible COVID-related aetiology. Proposed mechanisms include molecular mimicry between SARS-CoV-2 peptides and ACTH, cytokine-mediated hypothalamic–pituitary suppression via IL-6/TNF-α, and possible direct viral or microvascular damage to the hypothalamic–pituitary axis^1,2. Clinicians should consider IAD as a differential in patients with persistent post-COVID fatigue. Early recognition enables timely glucocorticoid replacement and optimised clinical management.

References: 1. Taieb D et al. Front Endocrinol (Lausanne). 2024; 15:10886368. 2. Bellastella G et al. Biomedicines. 2022; 10(11):2855.