Timing and type of glucocorticoid replacement in adult congenital adrenal hyperplasia.

Congenital adrenal hyperplasia (CAH) is one of the commonest inherited diseases. Treatment during childhood is directed towards obtaining normal growth. There is an extensive literature on management of CAH during childhood but little published on how patients should be treated as adults. CAH results in increased adrenocorticotropic hormone levels driving the adrenal to produce cortisol and thereby excessive cortisol precursors which are predominantly androgenic. In normal individuals there is a marked circadian rhythm in cortisol release with the lowest levels occurring shortly after midnight and rising between 02.00 and 03.00 h to peak at around 06.00-08.00 h after waking. The treatment of choice for children with CAH is hydrocortisone three times daily. There is no consensus on treating adults. A recent survey by the UK Society for Endocrinology showed that hydrocortisone was the most popular steroid, followed by dexamethasone and then prednisolone. Sixty percent of respondents used a reverse circadian pattern of glucocorticoid treatment and only 16% used a dose based on weight or surface area. In a recent study we demonstrated that the most important variable determining hydrocortisone bioavailability is weight and we advocated a weight-related dosing regimen monitored using a nomogram for serum cortisol. .