Biochemistry · Molecule
17-Hydroxyprogesterone (17-OHP) !
An intermediate of cortisol synthesis; it piles up when 21-hydroxylase is missing, which is why newborn screening measures it.
Updated 2026-11-01
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Key facts
- It is the 21-hydroxylase substrate on the cortisol pathway: 17-OHP → 11-deoxycortisol.
- It rises sharply in 21-hydroxylase deficiency and spills into androstenedione and testosterone.
- It is measured in heel-prick blood in newborn screening; prematurity and stress give false positives.
- In the non-classic form it may be normal at rest and rise only after ACTH stimulation.
- Also called
- 17-OHP, 17α-Hydroxyprogesterone
- Formula
- C21H30O3
- PubChem
- CID 6238
Structure
- Progesterone with a hydroxyl group on carbon 17α (a 21-carbon steroid).
- 17α-Hydroxylase (CYP17A1) makes it and 21-hydroxylase (CYP21A2) uses it up.
Clinical notes
- A very high 17-OHP in a newborn with ambiguous genitalia or with vomiting and low sodium points to congenital adrenal hyperplasia.
- In a woman with hirsutism it is measured in the early follicular phase to tell non-classic deficiency from polycystic ovaries.
- It also rises, though less, in 11β-hydroxylase deficiency.
Pathways
Related conditions
- Congenital adrenal hyperplasia due to 21-hydroxylase deficiency
- Congenital adrenal hyperplasia due to 11β-hydroxylase deficiency
- Polycystic ovary syndrome
Related
- 21-Hydroxylase (CYP21A2)
- 17α-Hydroxylase/17,20-lyase (CYP17A1)
- Adrenal enzymes and congenital adrenal hyperplasia
- Cortisol
Test yourself
Think of the answer, then tap the question to see it.
Which enzyme uses up 17-hydroxyprogesterone on the cortisol pathway?
21-Hydroxylase (CYP21A2), which turns it into 11-deoxycortisol.
Why can a premature newborn have a false-positive screen?
Because prematurity and stress raise 17-hydroxyprogesterone without any enzyme deficiency.
Which test is used when the non-classic form is suspected and basal 17-OHP is borderline?
ACTH stimulation, which makes 17-OHP rise sharply if 21-hydroxylase is deficient.
Molecules are shown in their neutral form, as the databases deposit them; in the cell the acids and phosphates are ionised.
Educational information, not medical advice. For any symptom, see a health professional.
Sources: 17-Hydroxyprogesterone (CID 6238) (PubChem, NCBI, 2026) · Public domain; 21-hydroxylase deficiency: MedlinePlus Genetics (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).
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