What is Cortisol Metabolites (a-Tetrahydrocortisol, b-Tetrahydrocortisol, Tetrahydrocortisone)?
Cortisol is metabolised by hepatic and peripheral enzymes (including 5-alpha and 5-beta reductases) to tetrahydro metabolites excreted in urine. The sum of these metabolites estimates total cortisol production, which can differ from free cortisol levels when clearance or peripheral metabolism is altered, for example in obesity or thyroid dysfunction. Measuring both free and metabolised cortisol aims to distinguish production from clearance effects.