[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Biochemistry](https://durgical.com/en/biochemistry/) › Adrenal enzymes and congenital adrenal hyperplasia [Biochemistry](https://durgical.com/en/biochemistry/) · Topic # Adrenal enzymes and congenital adrenal hyperplasia Which adrenal cortex enzyme makes each hormone, and what happens when one is missing: what comes before piles up and spills into another branch. Updated 2026-11-01 ## Key facts - Three branches from pregnenolone: mineralocorticoids (glomerulosa), glucocorticoids (fasciculata) and androgens (reticularis). - 17α-Hydroxylase (CYP17A1) picks the branch: without it pregnenolone can only go towards aldosterone. - In every CAH cortisol is short, ACTH rises and enlarges the gland; the precursors before the block pile up. - 21-Hydroxylase deficiency (95 %): salt loss and virilisation. 11β deficiency: virilisation and hypertension. 17α deficiency: hypertension with no androgens or oestrogens. - Rule of thumb: the deficiency that ends in 1 (21, 11β) virilises; the one that starts with 1 (11β, 17α) causes hypertension. ## In detail - Mineralocorticoid branch: pregnenolone → (3β-HSD2) progesterone → (CYP21A2) 11-deoxycorticosterone (DOC) → (CYP11B2) corticosterone → aldosterone. - Glucocorticoid branch: pregnenolone → (CYP17A1, 17α-hydroxylase) 17-hydroxypregnenolone → (3β-HSD2) 17-hydroxyprogesterone → (CYP21A2) 11-deoxycortisol → (CYP11B1) cortisol. - Androgen branch: 17-hydroxypregnenolone → (CYP17A1, 17,20-lyase) DHEA → androstenedione → testosterone; aromatase turns androgens into oestrogens. - 21-Hydroxylase deficiency: 17-hydroxyprogesterone piles up and spills into androgens; in the salt-wasting form aldosterone is also missing (low sodium, high potassium, high renin). - 11β-Hydroxylase deficiency: 11-deoxycortisol and DOC pile up; DOC acts as a mineralocorticoid and causes hypertension with low potassium and suppressed renin; androgens also rise. - 17α-Hydroxylase deficiency: no cortisol, androgens or oestrogens are made; everything goes to DOC and corticosterone (hypertension, hypokalaemia). Corticosterone partly stands in for cortisol, so adrenal crisis is rare. - Rarer forms: 3β-HSD2, StAR (lipoid hyperplasia, no steroid hormones at all) and P450 oxidoreductase (POR) deficiencies. - The shared treatment is glucocorticoid replacement: it corrects cortisol and, by holding ACTH back, lowers the piled-up precursors. **Also called** Adrenal steroidogenesis, CAH ## Clinical notes - Newborn screening measures 17-hydroxyprogesterone in heel-prick blood to find 21-hydroxylase deficiency before the salt-wasting crisis. - A newborn girl with ambiguous genitalia and a normal uterus and ovaries: think first of 21-hydroxylase deficiency. - A teenager with hypertension, low potassium and no puberty: think of 17α-hydroxylase deficiency. - Metyrapone inhibits 11β-hydroxylase and is used to test the axis and to treat cortisol excess. ## Pathways - [Adrenal cortisol synthesis](https://durgical.com/en/biochemistry/pathways/adrenal-cortisol-synthesis/) ## Related conditions - [Congenital adrenal hyperplasia due to 21-hydroxylase deficiency](https://durgical.com/en/conditions/congenital-adrenal-hyperplasia-due-to-21-hydroxylase-deficiency/) - [Congenital adrenal hyperplasia due to 11β-hydroxylase deficiency](https://durgical.com/en/conditions/congenital-adrenal-hyperplasia-due-to-11-hydroxylase-deficiency/) - [Congenital adrenal hyperplasia due to 17α-hydroxylase deficiency](https://durgical.com/en/conditions/congenital-adrenal-hyperplasia-due-to-17-hydroxylase-deficiency/) - [Adrenal insufficiency](https://durgical.com/en/conditions/adrenal-insufficiency/) - [Cushing syndrome](https://durgical.com/en/conditions/cushing-syndrome/) ## Related - [Steroid hormone synthesis (overview)](https://durgical.com/en/biochemistry/topics/steroid-hormone-synthesis/) - [21-Hydroxylase (CYP21A2)](https://durgical.com/en/biochemistry/enzymes/21-hydroxylase/) - [11β-Hydroxylase (CYP11B1)](https://durgical.com/en/biochemistry/enzymes/11-hydroxylase/) - [17α-Hydroxylase/17,20-lyase (CYP17A1)](https://durgical.com/en/biochemistry/enzymes/17-hydroxylase-17-20-lyase/) - [Aromatase (CYP19A1)](https://durgical.com/en/biochemistry/enzymes/aromatase/) - [Cortisol](https://durgical.com/en/biochemistry/molecules/cortisol/) - [Aldosterone](https://durgical.com/en/biochemistry/molecules/aldosterone/) - [17-Hydroxyprogesterone (17-OHP)](https://durgical.com/en/biochemistry/molecules/17-hydroxyprogesterone/) - [Cholesterol](https://durgical.com/en/biochemistry/molecules/cholesterol/) ## Test yourself Think of the answer, then tap the question to see it. ## Why does the adrenal gland enlarge in congenital adrenal hyperplasia? Because cortisol is short, the pituitary is not held back and the high ACTH keeps stimulating the cortex. ## Which precursor piles up in 21-hydroxylase deficiency and is used for screening? 17-Hydroxyprogesterone, which also spills into androgens. ## Why does 11β-hydroxylase deficiency cause hypertension? 11-Deoxycorticosterone piles up; it has mineralocorticoid action and retains sodium. ## Which hormones are missing in 17α-hydroxylase deficiency? Cortisol, androgens and oestrogens; production is diverted to DOC and corticosterone. ## Which treatment fixes both the cortisol shortage and the precursor excess? Glucocorticoid replacement, which holds ACTH back. [Add to my cards (5)](https://durgical.app/estudiar/?add=/en/biochemistry/topics/adrenal-enzymes-and-congenital-adrenal-hyperplasia/) Educational information, not medical advice. For any symptom, see a health professional. Sources: [Congenital adrenal hyperplasia: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/000411.htm) (MedlinePlus, US National Library of Medicine, 2026); [21-hydroxylase deficiency: MedlinePlus Genetics](https://medlineplus.gov/genetics/condition/21-hydroxylase-deficiency/) (MedlinePlus, US National Library of Medicine, 2026); [Congenital adrenal hyperplasia due to 11-beta-hydroxylase deficiency: MedlinePlus Genetics](https://medlineplus.gov/genetics/condition/congenital-adrenal-hyperplasia-due-to-11-beta-hydroxylase-deficiency/) (MedlinePlus, US National Library of Medicine, 2026); [17 alpha-hydroxylase/17,20-lyase deficiency: MedlinePlus Genetics](https://medlineplus.gov/genetics/condition/17-alpha-hydroxylase-17-20-lyase-deficiency/) (MedlinePlus, US National Library of Medicine, 2026); Textbook of Biochemistry for Medical Students, 6th ed. (Jaypee Brothers Medical Publishers (Vasudevan DM, Sreekumari S, Vaidyanathan K), 2011). [← All of biochemistry](https://durgical.com/en/biochemistry/) ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/biochemistry/topics/adrenal-enzymes-and-congenital-adrenal-hyperplasia/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/biochemistry/topics/adrenal-enzymes-and-congenital-adrenal-hyperplasia/