Free cortisol in spot urine analysis (Cortisol Free, Spot Urine) by liquid chromatography–tandem mass spectrometry (LC-MS/MS) is a precise test used to measure levels of free cortisol, the active form of the hormone cortisol, in a urine sample. Cortisol is an important hormone produced by the adrenal glands and plays a vital role in regulating many biological processes, including the body’s response to stress, control of blood sugar levels, and metabolism. A random urine sample is collected, which facilitates the analysis without the need for 24-hour urine collection. This test is important in diagnosing adrenal gland disorders such as Cushing’s syndrome, where cortisol levels are abnormally high, or adrenal insufficiency, where levels are low. LC-MS/MS technology is among the most accurate methods for measuring cortisol levels, contributing to a comprehensive assessment of adrenal gland function.