21-deoxycortisol

21-deoxycortisol (21DO) is a steroid metabolite and marker of congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency (21OHD). 21DO is produced within the adrenals by the action of 11β-hydroxylase on 17-hydroxyprogestone (17OHP), itself a steroid precursor which accumulates in 21OHD CAH. Although 17OHP is primarily used to diagnose 21OHD CAH, the test can suffer with issues of specificity, as it is increased in other physiological (preterm infants and in the luteal phase of the menstrual cycle) and pathophysiological (other forms of CAH, such as 3β-hydroxysteroid dehydrogenase deficiency) conditions. On the other hand, 21-deoxycortisol is not typically increased in preterm infants, is specific for 21OHD CAH and, as a product of adrenal 11β-hydroxylase activity, is only synthesised by the adrenal glands (not the gonads). 21-deoxycortisol has therefore been recommended as a replacement for 17OHP for 21OHD CAH diagnosis, but it is recognised that laboratories and clinicians will require time to adapt and become familiar with 21-deoxycortisol measurements. We therefore recommend 21-deoxycortisol measurement as an adjuvant to 17OHP measurement. Please note, for a period of 6 months from 22nd May 2023 we will be reporting a 21-deoxycortisol result with every raised 17OHP, adding specificity to the 17OHP result. There will be no charge from Synnovis for this additional result. After this time, 21-deoxycortisol will revert to being a user requested, billable service.