Regarding the Hypothalamic-Pituitary-Adrenal (HPA) axis suppression by long-term corticosteroid therapy, which statement is most accurate?

• A Even low-dose (>7.5 mg/day prednisolone equivalent) daily therapy for >3 weeks can cause HPA suppression requiring gradual tapering ✓
• B HPA suppression occurs only with oral prednisolone doses exceeding 20 mg/day for more than 1 year
• C Inhaled corticosteroids never cause significant HPA suppression
• D HPA suppression after long-term therapy reverses completely within 48 hours of stopping

Explanation

Exogenous corticosteroids suppress the HPA axis by negative feedback at the hypothalamus (reducing CRH) and pituitary (reducing ACTH). With doses equivalent to 7.5 mg/day prednisolone or more for more than 2-3 weeks, the adrenal cortex may undergo functional atrophy and require weeks to months to recover full cortisol secretory capacity. Abrupt withdrawal can cause adrenal insufficiency, especially during physiological stress. The timing and degree of suppression vary, but prudent practice dictates tapering any corticosteroid course lasting more than 3 weeks. Inhaled corticosteroids at high doses (e.g., fluticasone >1000 mcg/day) can also cause measurable HPA suppression, particularly in children.

Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.

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Written and medically reviewed by the StethoPrep medical team.