17-OH progesterone ng/mL → nmol/L
Convert 17-oh progesterone from ng/mL to nmol/L
Sources last checked: 2026-11-03
17-OH progesterone ng/mL → nmol/L
Convert 17-oh progesterone from ng/mL to nmol/L
Converts units only; reference ranges depend on the laboratory, the assay and the patient.
What is the 17-OH progesterone ng/mL → nmol/L?
17-hydroxyprogesterone (17-OHP) is the main marker for 21-hydroxylase deficiency, the commonest form of congenital adrenal hyperplasia. Many laboratories in Germany, Austria, Turkey and the USA report it in ng/mL, while the UK and much of the European literature use nmol/L. This converter multiplies by 3.026, derived from the molar mass of 17-OHP (330.5 g/mol).
When to use it
- Comparing a basal or ACTH-stimulated 17-OHP in ng/mL with a guideline or paper written in nmol/L
- Work-up of suspected non-classic congenital adrenal hyperplasia in women with hyperandrogenism
- Monitoring treated congenital adrenal hyperplasia when results come from laboratories using different units
- Exam questions on adrenal enzyme defects
When not to use it
- Neonatal screening results from dried blood spots, which are measured in whole blood with screening-specific cut-offs and are not directly comparable with serum values
- Progesterone or 17-hydroxypregnenolone, which are different steroids with different molar masses
- Transferring a threshold between immunoassay and LC-MS/MS: the conversion is exact, the cut-offs are method-specific
How it is calculated
17-OHP (nmol/L) = 17-OHP (ng/mL) × 3.026
Clinical pearls and limitations
- Converts units only; reference ranges depend on the laboratory, the assay and the patient.
- 1 ng/mL = 3.026 nmol/L; conversely 1 nmol/L = 0.3305 ng/mL.
- 17-OHP has a morning peak and, in women, rises in the luteal phase; protocols usually specify early-morning sampling in the follicular phase.
- Immunoassays can overestimate 17-OHP, particularly in neonates and preterm infants, through cross-reacting steroids; LC-MS/MS is more specific and is often used as a second-tier test.
- Stress, illness and prematurity raise 17-OHP in newborns, so screening programmes use birth-weight- or gestational-age-adjusted cut-offs.
Frequently asked questions
How do I convert 17-OH progesterone from ng/mL to nmol/L?
Multiply by 3.026. For example, 3.7 ng/mL × 3.026 = 11.2 nmol/L.
Why is the 17-OHP factor 3.026?
17-OHP has a molar mass of 330.5 g/mol. 1 ng/mL equals 1 µg/L, and 1000 ÷ 330.5 = 3.026 nmol/L.
Can I apply an adult 17-OHP cut-off to a newborn?
No. Neonatal values depend on gestational age, birth weight, age at sampling and stress, and screening uses whole-blood spots with programme-specific thresholds.
Evidence and guidelines
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<p><a href="https://medelix.ai/en/calculators/17-oh-progesterone-ng-ml-to-nmol-l">17-OH progesterone ng/mL → nmol/L calculator by Medelix</a></p>For healthcare professionals and medical students. These tools support, and do not replace, clinical judgement. Always check results against the original source and your local protocols.