Monitoring
Recurrence of adrenocorticotrophic hormone-dependent Cushing syndrome is common, with at least a 5% to 26% risk of recurrence at 5 years. Screen patients who have achieved remission after hypothalamic-pituitary-adrenal (HPA) axis recovery for recurrence of disease and then annually or sooner if there is clinical suspicion.[26] Use one of four high-sensitivity tests (late-night salivary cortisol, 1 mg overnight dexamethasone suppression testing, 24-hour urinary free cortisol, or desmopressin testing) to detect recurrence. Late-night salivary cortisol is the most sensitive test for detecting recurrence and should be done annually after HPA axis recovery postoperatively and then annually.[26]
Many patients are supported with corticosteroids following pituitary surgery but should be assessed for remission during the first postoperative week.[68] This is most easily done by measurement of the morning cortisol at least 24 hours after the last dose of corticosteroid therapy. Patients with a postoperative morning cortisol of <55 nanomol/L (<2 micrograms/dL) are considered to be in remission and can transition into long-term follow-up. Patients with a postoperative morning cortisol of >138 nanomol/L (>5 micrograms/dL) require further evaluation and possibly further therapy. Patients with a morning cortisol between 55 and 138 nanomol/L (2 and 5 micrograms/dL) should be followed with additional morning measurements to detect a drop in subsequent cortisol levels. Individuals with morning cortisols >55 nanomol/L (>2 micrograms/dL) after surgery are 2.5 times more likely to have recurrences than those with cortisol levels <55 nanomol/L (<2 micrograms/dL).[72]
As postoperative hypocortisolism is predictive of remission, some centres advocate withholding routine corticosteroid therapy after pituitary surgery and monitoring cortisol levels every 8 hours or if symptoms of adrenal insufficiency occur.[74] If adrenal insufficiency occurs or low cortisol levels are documented, corticosteroid therapy should be initiated. Other centres begin routine corticosteroid therapy immediately after surgery and evaluate for remission of hypercortisolism later in the postoperative course. Corticosteroids are usually rapidly tapered to physiological doses within 1 week or less (often by discharge from hospital). Testing to see if the hypothalamic-pituitary-adrenal axis has recovered can be done in follow-up by 3 months after surgery. Testing is usually a morning cortisol prior to the patient taking the morning hydrocortisone dose, if continued. Cortisol levels of >552 nanomol/L (>20 micrograms/dL) indicate recovery of the axis. Levels <83 nanomol/L (<3 micrograms/dL) indicate continued need for corticosteroids. Levels between 83 nanomol/L (3 micrograms/dL) and 552 nanomol/L (20 micrograms/dL) should prompt further testing (cosyntropin stimulation testing, insulin tolerance testing, or metyrapone testing).
Standard testing, follow-up, and management for associated conditions of hypertension, diabetes, and osteoporosis should be undertaken, as these conditions may persist after effective treatment of hypercortisolism.
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