Walk-In Lab's urinary free cortisol test helps with the initial evaluation of patients with suspected Cushing syndrome (CS). Patients with CS usually have urine free cortisol >100 μg/24 hours, but there is wide variation and no single cutoff can be used safely. If the 24-hour urine free cortisol is elevated, additional testing is typically needed to determine whether a patient has pituitary-dependent CS, pituitary-independent CS or pseudo-Cushing syndrome.
Pseudo-Cushing syndrome occurs when patients with an elevated 24-hour urine cortisol do not have Cushing syndrome. This diagnosis requires additional testing which includes the CRH stimulation test, the low-dose dexamethasone suppression test or a protocol that combines both.
A meticulous history and physical examination are required when diagnosing CS, and should be performed prior to any biochemical evaluations like a urinary free cortisol test.
Includes Creatinine (which is used to evaluate the health of the kidneys).
