Adrenal Crisis Masquerading as Sepsis in a Patient With Autoimmune Multimorbidity: A Diagnostic Challenge on the Acute Medical Ward

A patient in her mid-60s with autoimmune multimorbidity, including cutaneous lupus, Sjögren's syndrome, antiphospholipid syndrome (APLS), and adrenal insufficiency, presented with a five-day history of fever, vomiting, diarrhea, and profound fatigue. Adrenal crisis typically occurs in individuals with adrenal insufficiency during periods of physiological stress such as infection, dehydration, surgery, or inadequate steroid dosing, and should be suspected when patients develop hypotension, gastrointestinal upset, electrolyte disturbances, or fail to improve with standard therapy. Because these symptoms overlap significantly with sepsis, diagnostic confusion is common, especially in acutely unwell immunosuppressed patients, where infection is frequently presumed. Sepsis itself presents with fever, raised inflammatory markers, hypotension, and generalized malaise, mirroring many manifestations of adrenal crisis and often leading to initial misclassification. Despite correctly applying steroid sick-day rules, which involve doubling usual glucocorticoid doses during acute illness, patients may still decompensate and require escalation to parenteral emergency doses. In this case, empirical antibiotics were started for presumed sepsis after investigations revealed raised C-reactive protein (CRP) and mild hypokalemia with no clear infectious focus. However, the rapid improvement following fluid resuscitation and adjusted steroid therapy highlighted adrenal crisis as the true underlying cause. This case emphasizes the importance of maintaining a high index of suspicion for adrenal crisis in any acutely ill patient with known adrenal insufficiency, ensuring timely stress-dose steroid administration before pursuing alternative differential diagnoses.