Introduction: Long‑term glucocorticoid (GC) therapy is the most common cause of secondary adrenal insufficiency (AI), which undiagnosed may lead to life‑threatening adrenal crisis.
Objectives: The aim of the study was to evaluate AI in patients treated long‑term with GCs, receiving a low maintenance dose (≤5 mg of prednisone or equivalent), namely, its prevalence and persistence, risk factors, and diagnostic accuracy of morning cortisol and dehydroepiandrosterone sulfate (DHEA‑S) levels.
Patients and methods: Adrenal function was evaluated in 40 patients before and after GC withdrawal and at least 1 year later. Based on morning cortisol levels and short Synacthen test, patients were divided into 3 groups: AI, intermediate (partial AI), and AS (adrenal sufficiency). Receiver operator characteristic curves were calculated to assess the diagnostic value of morning cortisol and DHEA‑S levels before GC withdrawal.
Results: Before GC withdrawal, 42.5% of patients had AI or partial AI, which together persisted in 64.3% of those patients after withdrawal. After more than a year, the adrenal function returned to normal only in 14% of patients. Cushingoid feature occurred more often in the AI group compared with the AS group (60% vs 13%; P = 0.03). Morning cortisol levels of 14.91 μg/dl or higher (411 nmol/l) gave 100% negative predictive value to rule out AI. Morning cortisol of 6.51 μg/dl or less (179.6 nmol/l) gave 100% positive predictive value to rule in AI. DHEA‑S proved to be a worse parameter for AI diagnosis.
Conclusions: AI is common in patients treated with GCs and may persist for years after GC withdrawal. Cushingoid features are associated with a higher risk of AI. Morning cortisol levels may facilitate AI diagnosis.