The reasons for this discrepancy are unclear; while increased cortisol clearance may explain this observation D8-corticosterone levels were not lower than anticipated and the half-life of hydrocortisone in patients with CAH is not reduced.34 Nevertheless, despite ∼2.5-fold higher D8-corticosterone than cortisol concentrations, both compounds induced almost identical reductions in ACTH, 17OHP, androstenedione and testosterone concentrations. Here, POMC is linked to congenital adrenal hyperplasia.