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A study has revealed that serum progesterone concentrations in boys (10 days to 18 years old) with 21-hydroxylase deficiency reached levels up to 10.14 ng/mL, i.e. similar to female luteal values, while in the control group of boys, average level was 0.07 ng/mL (0.22 nmol/L), with values ranging from 0.05 to 0.40 ng/mL. [38]
The condition of 21-hydroxylase deficiency is screened by measuring serum levels of 17α-hydroxyprogesterone (17-OHP) in the morning and between day 3 and 5 of the menstrual cycle (for females) to reduce the possibility of false positive results. [12] 17-OHP is used as a marker of the 21-hydroxylase enzyme activity since the 1980s. [52]
Steroid 21-hydroxylase is a protein that in humans is encoded by the CYP21A2 gene. The protein is an enzyme that hydroxylates steroids at the C21 position on the molecule. [ 10 ] [ 11 ] Naming conventions for enzymes are based on the substrate acted upon and the chemical process performed.
Autoimmune destruction of the adrenal cortex is caused by an immune reaction against the enzyme 21-hydroxylase (a phenomenon first described in 1992). [20] This may be isolated or in the context of autoimmune polyendocrine syndrome (APS type 1 or 2), in which other hormone-producing organs, such as the thyroid and pancreas , may also be affected.
References range may vary with age, sex, race, pregnancy, [10] diet, use of prescribed or herbal drugs and stress. Reference ranges often depend on the analytical method used, for reasons such as inaccuracy, lack of standardisation, lack of certified reference material and differing antibody reactivity. [11]
21-deoxycortisol is a marker of congenital adrenal hyperplasia due to 21-hydroxylase deficiency, [2] [1] [3] even in mild (non-classic) cases. [4] [5] It can be also used for newborn screening. [6] The deficiency of the 21-hydroxylase enzyme leads to excess of 17α-hydroxyprogesterone, [7] [8] a 21-carbon (C 21) steroid.
The most common forms of this condition impair both the 17α-hydroxylase activity and the 17,20-lyase activity of CYP17A1. Like other forms of CAH, 17α-hydroxylase deficiency impairs the efficiency of cortisol synthesis, resulting in high levels of ACTH secretion and hyperplasia of the adrenal glands.
It has been known since 1987 that increased levels of 11β-OHP occur in 21-hydroxylase deficiency. [6] [7] A study in 2017 has shown that in subjects with 21-hydroxylase deficiency, serum 11β-OHP concentrations range from 0.012 to 3.37 ng/mL, while in control group it was below detection limit of 0.012 ng/mL.