Clinical Information

Serum cortisol is used for discrimination between primary and secondary adrenal insufficiency, and differential diagnosis of Cushing syndrome. Serum cortisol testing is not used for screening, diagnosing, or excluding Cushing’s syndrome, and is not used for monitoring replacement treatment in patients with adrenal deficiency. This test is not recommended for evaluating response to metyrapone. Circulating cortisol results from patients receiving prednisolone or prednisone (which is converted to prednisolone in vivo) therapy may be falsely elevated. Exercise caution with cortisol determinations for patients undergoing therapy with these and structurally related synthetic corticosteroids. Patients receiving metyrapone may show artificially elevated cortisol values due to the accumulation of 11-deoxycortisol. The performance of the assay has not been established with neonatal specimens. For assays employing antibodies, the possibility exists for interference by human anti-animal antibodies (i.e., heterophile antibodies) in the patient sample. Patients who have been regularly exposed to animals or have received immunotherapy or diagnostic procedures utilizing immunoglobulins or immunoglobulin fragments may produce antibodies, (eg, HAMA), that interfere with immunoassays. This may falsely elevate or falsely decrease the results.