Description
The 17-Hydroxyprogesterone (17-OHP) Test from BiomarkersLabs.com measures serum 17-hydroxyprogesterone — a steroid hormone intermediate in the adrenal cortisol and sex hormone biosynthesis pathways, produced primarily by the adrenal cortex and, in smaller amounts, by the ovaries. The primary clinical significance of 17-OHP measurement is in the diagnosis and monitoring of congenital adrenal hyperplasia (CAH) — particularly the most common form, 21-hydroxylase deficiency, in which the enzyme defect causes 17-OHP to accumulate as cortisol synthesis is blocked. This accumulation diverts adrenal precursors into androgen synthesis pathways, causing androgen excess.
Non-classical (late-onset) CAH due to 21-hydroxylase deficiency is significantly more prevalent than the classical form and is a well-recognised mimic of PCOS in women of reproductive age, presenting with hirsutism, oligomenorrhoea, acne, and anovulation. Differentiating non-classical CAH from PCOS has direct implications for management, as CAH is treated with low-dose glucocorticoid therapy to suppress adrenal androgen overproduction, while PCOS is managed differently. 17-OHP is also measured in newborn screening programmes for classical CAH, where prompt diagnosis prevents life-threatening adrenal crises. Results are CLIA-certified (USA) and IVDR-compliant (EU/UK), delivered to the practitioner portal within 1–3 business days.
What does the 17-Hydroxyprogesterone Test measure?
17-Hydroxyprogesterone (17-OHP) — adrenal steroid intermediate in cortisol biosynthesis. Markedly elevated in classical 21-hydroxylase deficiency CAH; moderately elevated in non-classical CAH. Morning follicular-phase values (Day 2–5) are the standard reference. A basal 17-OHP above 6 nmol/L (2 ng/mL) in the follicular phase is highly suggestive of non-classical CAH; values above 30 nmol/L virtually confirm the diagnosis. ACTH stimulation testing provides definitive diagnosis where basal levels are borderline. 17-OHP is always most informative when interpreted alongside testosterone, DHEA-S, and SHBG in the androgen excess workup.
Clinical indications
Non-classical CAH differentiation from PCOS — 17-OHP is the key differentiating test between PCOS and non-classical 21-hydroxylase deficiency CAH, which share overlapping clinical features of hyperandrogenism and menstrual irregularity but require different treatment approaches.
Hirsutism and hyperandrogenism workup — adrenal cause screening — in women with clinical signs of androgen excess, 17-OHP screens for adrenal enzyme deficiency as an underlying cause alongside testosterone, DHEA-S, and SHBG.
Classical CAH monitoring — in patients with known classical CAH on glucocorticoid replacement, 17-OHP monitoring guides dosing adequacy — suppression to normal range indicates adequate treatment; persistently elevated values indicate under-replacement.
Newborn and paediatric CAH assessment — 17-OHP is the primary biochemical marker for classical CAH in newborns and infants presenting with ambiguous genitalia, salt-wasting, or newborn screening abnormalities.
Adrenal androgen excess investigation — alongside DHEA-S, in women where adrenal rather than ovarian androgen production is suspected as the primary driver of hyperandrogenism.
Pre-conception assessment in known CAH carriers — women with a family history of CAH or known carrier status benefit from 17-OHP measurement and genetic counselling before conception.
Sample type and collection
Blood (serum). No fasting required. Venepuncture at an approved collection site. Morning collection on Day 2–5 of the menstrual cycle (early follicular phase) is the standard reference timing, as 17-OHP follows a diurnal pattern and rises in the luteal phase, potentially causing false-positive results if collected at other cycle phases. In women with amenorrhoea, morning collection at any time is appropriate. Cycle day at draw must always be documented.
Turnaround time
1–3 business days from specimen receipt.
Availability
USA · EU · UK · Canada
Compliance
CLIA Certified · IVDR Compliant · CE Marked · HIPAA Compliant · GDPR Compliant · PIPEDA Compliant
How to order
Register free at BiomarkersLabs.com. Licensed practitioners only. Pay per test — no subscription required. Results are delivered directly and securely to your practitioner portal and are never released directly to patients.
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