The diagnosis of Cushing's syndrome

Spontaneous Cushing's syndrome is well known but unusual clinical disorder. Many of the clinical features (central weight gain, glucose intolerance, hypertension, muscle weakness) are seen in other common conditions. Recognition of patients with multiple features, features unusual for their age (i.e. early onset osteoporosis or hypertension), patients with features more specific to Cushing's syndrome (i.e. easy bruising, facial plethora, and violaceous striae), and patients with incidental adrenal mass or polycystic ovary syndrome should prompt an evaluation for cortisol excess. Late-night salivary cortisol, 1 mg overnight dexamethasone suppression testing, or 24 h urine free cortisol determination have excellent diagnostic characteristics and should be obtain in patients with suspected Cushing' syndrome. If this initial testing is abnormal, further evaluation should be directed by an endocrinologist experienced in the diagnosis and differential diagnosis of Cushing' syndrome.