La diagnostica di laboratorio delle malattie del surrene. Raccomandazioni pratiche per la sindrome di Cushing

Cushing’s syndrome comprises several signs and symptoms due to chronic exposure to high endogenous and exogenous levels of glucocorticoids. Most of the cases of Cushing’s syndrome are caused by ACTH secretion from pituitary tumors (Cushing’s disease); some forms of Cushing’s syndrome are caused by cortisol-secreting adrenal tumors. The most common clinical features are central obesity, strie rubrae, acne, hirsutism, muscle weakness, osteoporosis, gonadic dysfunctions (hypogonadotropic hypogonadism in male, oligo- or anovulatory cycles in females), blood hypertension, metabolic dysfunctions (diabetes mellitus and hyperlipidemia), psychiatric disorders (depression and psychosis). The subclinical forms are more common and are found in 5–20% of adrenal incidentaloma. The review of the literature from 2009 to 2015 substantially confirms 2008 Endocrine Society guidelines: diagnostic odd ratio and number needed to diagnose prove that urinary free cortisol, late-night salivary cortisol and dexamethasone suppression test yield very satisfactory and comparable performances. The present practical recommendations of the Italian Society of Clinical Pathology and Laboratory Medicine are consistent with those published by Endocrine Society, highlighting the diagnostic role of the late-night salivary cortisol (at least two samples in two different days), determined by an immunoassay with a proper cut-off, or a LC-MS/MS method. The importance of standardizing the saliva collection is confirmed, coupled with an adequate device and detailed information for the patient. We recommend against random serum cortisol and plasma ACTH samples, urinary 17-ketosteroids, insulin tolerance test, loperamide test, 8 mg dexametasone.