Medical Treatment for Cushing Syndrome

Initial Management of Iatrogenic Cushing Syndrome

The American College of Endocrinology recommends immediately discontinuing the causative glucocorticoid if medically feasible, followed by gradual tapering to prevent adrenal insufficiency 1
For patients with iatrogenic Cushing syndrome, stopping all sources of exogenous glucocorticoids, including oral, injectable, inhaled, and topical preparations, is crucial 1
Tapering gradually rather than abrupt cessation is necessary to avoid precipitating adrenal crisis, as the hypothalamic-pituitary-adrenal (HPA) axis remains suppressed 1
Considering switching to lower-dose inhaled steroids or alternative medications for the underlying condition if complete discontinuation is not possible 1

For patients with hypertension due to Cushing syndrome, using spironolactone 25-50 mg daily or eplerenone 50-100 mg daily as first-line therapy is recommended, as these mineralocorticoid receptor antagonists directly counteract cortisol's mechanism of causing hypertension 1, 2
Initiating metformin as first-line therapy for hyperglycemia, or considering GLP-1 receptor agonists or DPP-4 inhibitors, and monitoring blood glucose closely during taper is essential 1
Prescribing calcium 1000-1500 mg daily and vitamin D 800-1000 IU daily immediately for patients who received prednisone >7.5 mg daily for >3 months to prevent osteoporosis 1

Assessing body weight to track resolution of central obesity is important 1
Monitoring blood pressure at each visit 1
Checking fasting glucose or HbA1c every 4-8 weeks 1
Monitoring serum potassium if on mineralocorticoid antagonists, at each dose reduction (every 2-4 weeks) 1
Measuring morning cortisol level once daily dose reaches physiologic range (≤5 mg prednisone) to assess HPA axis recovery 1

Mifepristone (glucocorticoid receptor blocker) can be considered for severe cases of hypercortisolism with complications, though it requires careful monitoring as cortisol levels remain elevated and only clinical features can assess treatment response 3, 1
Continuing stress-dose coverage until HPA axis recovery is confirmed, which may take up to 12 months after prolonged high-dose therapy, is necessary 1

The Endocrine Society recommends adrenal steroidogenesis inhibitors as the first-line medical therapy for endogenous Cushing syndrome, with ketoconazole, osilodrostat, or metyrapone as preferred agents 3, 4

Ketoconazole dosing is 400-1200 mg/day orally, divided twice daily, with approximately 65% achieving urinary free cortisol (UFC) normalization initially 4
Osilodrostat dosing is 2-7 mg twice daily orally, with 86% achieving UFC normalization in Phase 3 studies 4
Metyrapone dosing is 500 mg/day to 6 g/day, with approximately 70% achieving UFC normalization and rapid decrease in UFC typically within the first month 4, 2

For mild disease, ketoconazole, osilodrostat, or metyrapone are typically preferred 3
For moderate disease with residual tumor, cabergoline or pasireotide may be preferred due to potential for tumor shrinkage 3
For severe disease, rapid normalization of cortisol is the most important goal, and osilodrostat and metyrapone provide response within hours 3

Mifepristone blocks cortisol action at the glucocorticoid receptor regardless of etiology, with 60% achieving ≥25% reduction in glucose area under the curve after 24 weeks 3

Mineralocorticoid receptor antagonists (spironolactone or eplerenone) are the most effective antihypertensive agents, as they block mineralocorticoid receptor activation by excess cortisol 2

Multiple serial tests of both UFC and late-night salivary cortisol (LNSC) are used to monitor treatment outcomes 3
UFC average is 2-3 collections, and LNSC is ≥2 on consecutive days 4