A 38-year-old woman with systemic lupus erythematosus is started on long-term corticosteroid therapy. Which is the most common endocrine side effect of chronic corticosteroid administration?

Explanation

## Most Common Endocrine Side Effect of Chronic Corticosteroids **Key Point:** Suppression of the hypothalamic-pituitary-adrenal (HPA) axis is the most common and clinically significant endocrine complication of chronic corticosteroid therapy. ### Mechanism of HPA Axis Suppression ```mermaid flowchart TD A[Exogenous Corticosteroid]:::action --> B[Elevated serum cortisol]:::outcome B --> C[Negative feedback to hypothalamus]:::action C --> D[Decreased CRH release]:::outcome D --> E[Decreased ACTH from anterior pituitary]:::outcome E --> F[Reduced endogenous cortisol synthesis]:::outcome F --> G[HPA Axis Suppression]:::outcome G --> H[Risk of adrenal crisis on withdrawal]:::urgent ``` ### Timeline and Dose-Dependency | Corticosteroid Dose | Duration | HPA Suppression Risk | |---------------------|----------|---------------------| | <7.5 mg/day prednisolone | Any duration | Minimal | | 7.5–20 mg/day | >2 weeks | Moderate | | >20 mg/day | >1 week | High | | Any dose | >3 weeks | Significant | **High-Yield:** HPA axis suppression can occur within 1–2 weeks of starting corticosteroids at doses >20 mg/day prednisolone equivalent, and recovery may take 6–12 months after discontinuation. ### Clinical Consequences of HPA Suppression 1. **Loss of cortisol responsiveness to stress** — inability to mount appropriate cortisol response during acute illness, surgery, or trauma 2. **Adrenal crisis risk** — hypotension, hyponatremia, hyperkalemia, shock if corticosteroids are abruptly withdrawn 3. **Impaired immune response** — reduced ability to fight infections during stress 4. **Fatigue and malaise** — from chronic cortisol insufficiency **Clinical Pearl:** A patient on chronic corticosteroids who undergoes surgery without perioperative corticosteroid supplementation is at risk of intraoperative hypotension and cardiovascular collapse. ### Management of HPA Suppression **Key Point:** Patients on chronic corticosteroids require: - **Gradual tapering** (not abrupt cessation) — reduce by 10% every 1–2 weeks - **Stress dosing** — increase corticosteroid dose during acute illness, surgery, or trauma (e.g., 50–100 mg IV hydrocortisone during major surgery) - **HPA axis recovery assessment** — perform short Synacthen test (ACTH stimulation test) before complete withdrawal **Mnemonic: STRESS** — **S**urgery/Stress requires **T**emporary increase, **R**apid tapering is dangerous, **E**ndogenous production is suppressed, **S**upplementation needed, **S**ynacthen test for recovery ### Why This is Most Common HPA axis suppression occurs in virtually all patients on chronic corticosteroids (>2–3 weeks at therapeutic doses). It is universal and dose-dependent, whereas thyroid dysfunction and primary adrenal insufficiency are rare side effects of exogenous corticosteroids. **Warning:** Do NOT confuse secondary adrenal insufficiency (from HPA suppression) with primary adrenal insufficiency. In secondary insufficiency, aldosterone production is preserved (ACTH is suppressed), whereas in primary insufficiency, both cortisol and aldosterone are deficient. [cite:Harrison 21e Ch 397; KD Tripathi 8e Ch 56]