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17-Hydroxyprogesterone (17-OHP)

A steroid hormone made by the adrenal glands and ovaries. Clinicians use it mainly to look into congenital adrenal hyperplasia (CAH), an inherited enzyme condition.

AI-verified against cited sources. Awaiting expert reviewAlso called 17-OHP, 17OHP, 17-OH-PLOINC 1668-3

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What it is

17-hydroxyprogesterone (17-OHP) is a hormone your adrenal glands make on the way to cortisol. Your ovaries or testes make smaller amounts. An enzyme called 21-hydroxylase normally moves 17-OHP along to the next step. If that enzyme is weak or missing, 17-OHP builds up in the blood. In women, levels also rise after ovulation, so the usual range is different in each half of the menstrual cycle.

Why it matters

The test is used most often to look into congenital adrenal hyperplasia (CAH), most often caused by low 21-hydroxylase activity. It is also ordered when a woman has signs of extra male-type hormones, such as acne, extra hair growth or irregular periods, and as part of a PCOS work-up. People treated for CAH have it checked to see how treatment is working. A result is only one clue, so it is read with the time of day, the cycle phase and other hormone tests.

If it’s low

A low result is usually not a concern. It is common in the first half of the cycle, after menopause and in children before puberty. Steroid medicines (glucocorticoids) lower it on purpose in people treated for CAH. For them, the target is set by their clinician rather than the usual range.

Common causes

  • The early part of the menstrual cycle, or life after menopause
  • Steroid medicines such as prednisone or dexamethasone, which quiet the adrenal glands
  • Treatment for congenital adrenal hyperplasia that is working as planned
  • A sample drawn later in the day, after the morning peak
  • Normal variation between people

What can help

  • Tell your clinician about every steroid medicine you take, including pills and injections
  • If you are treated for CAH, ask what result range your clinician is aiming for

If it’s high

A result above your lab's range can have an ordinary explanation. If you have periods, a sample from the second half of the cycle will often look high next to the first-half range, even though it is typical for that time. The best-known medical cause is CAH. In the severe (classic) form, levels are typically in the thousands of ng/dL. Milder (nonclassic) CAH can give smaller rises. Many other things can raise 17-OHP, so your clinician will usually repeat the test or add others.

Common causes

  • A sample from the second half of the menstrual cycle compared with the first-half range
  • Premature newborns, who normally run high
  • A lab method (immunoassay) that picks up similar steroids and reads high
  • Congenital adrenal hyperplasia, either the severe or the milder form
  • Other less common enzyme problems in the adrenal glands, or hormone-making tumors of the adrenal gland or ovary

What can help

  • Ask whether your sample was drawn in the early morning and, if you have periods, in the first half of your cycle
  • Ask whether a repeat test with a more precise lab method (mass spectrometry), or a stimulation test, would help
  • Tell your clinician about any steroid medicines you take

Usual ranges

What labs print as the reference range, by who was tested. Ranges differ a little between labs, so the range on your own report is the one your result is judged against.

The usual range depends on sex. Choose women or men to see the one that applies.

If this applies to you

17-OHP means a little more for some people. Open the one that fits you.

PCOS

17-OHP helps check for nonclassic congenital adrenal hyperplasia, a mild form of an adrenal condition people are born with that can cause extra androgens. The PCOS guideline lists 17-OHP among the tests that rule out other causes.

Blood tests for PCOS

What can affect your result

  • Sex and cycle phase: higher after ovulation than before it
  • Time of day: early-morning samples are preferred
  • Age: newborns, especially premature babies, run high, and children before puberty run lower than adults
  • Method: LC-MS/MS and immunoassay can give different numbers
  • Steroid medicines, which lower it
  • Cycle phase: levels rise after ovulation, so the same blood level can be in range in the second half of the cycle and above range in the first.
  • Method: older immunoassays can read falsely high because other steroids cross-react, especially in newborns. LC-MS/MS is more specific, and ranges from the two methods are not interchangeable.
  • Steroid medicines (glucocorticoids) quiet the adrenal glands and lower 17-OHP.
  • The Mayo send-out listing rejects serum from a gel tube and samples that are grossly hemolyzed or lipemic, while Labcorp's directory accepts a gel-barrier tube, so follow the tube instructions from your own lab.
  • Premature newborns normally have high values, so results in babies are read against age- and gestation-specific ranges.

Early morning, before about 8 a.m. For people who menstruate, the Endocrine Society suggests the early follicular phase (the first days after a period starts). A single result is a snapshot. It tends to be higher in the morning, which is why early-morning samples are preferred, and in women it follows the cycle.

When to talk to a clinician

Contact the clinician who ordered the test if your lab flagged the result. Seek urgent care for repeated vomiting, severe weakness, fainting, confusion or signs of dehydration, especially if you or your child has known CAH or takes steroid medicines. If you feel very unwell, call 911 or your local emergency number.

Questions you could ask

  • Which lab method was used, and does my range match it?
  • How does this result fit with my other hormone tests?
  • Was my blood drawn at the right time of day and, if I have periods, the right time in my cycle?
  • Would a repeat test with a more precise lab method (mass spectrometry), or a stimulation test, help clarify this result?
  • Could a steroid medicine I take explain this result?

Questions people ask

Why does my range depend on where I am in my cycle?

After ovulation the ovary makes more hormones in this family, so 17-OHP is higher in the second half of the cycle. Labs print one range for the first half and a wider one for the second half. A result that looks high in the first half can be ordinary in the second half.

Why do different labs give different ranges?

Labs use different methods and different groups of healthy people to set their ranges. For adult men, the upper limit runs from 139 at one lab to 220 at another. Compare your result with the range printed on your own report.

How do I convert ng/dL to nmol/L?

Multiply ng/dL by 0.0303, so 100 ng/dL is about 3.0 nmol/L. To go the other way, multiply nmol/L by 33.05.

Show the science and sources

Units

  • 1 ng/dL = 1 ng/dL
  • 1 ng/dL = 0.03026 nmol/L
  • 1 ng/dL = 0.01 ng/mL

Open the 17-OHP unit converter

Is a change real?

17-OHP naturally varies about 23% from test to test in the same healthy person. Between two results from the same lab, a rise of 102% or more, or a fall of 51% or more, is unlikely to be day-to-day noise or lab variation (95% reference change value). Source: Sex Hormones and Adrenal Steroids: Biological Variation Estimated Using Direct and Indirect Methods (Roys EA et al.).

For clinicians and researchers

17-OHP is the substrate for 21-hydroxylase (CYP21A2), so it accumulates in 21-hydroxylase deficiency, which accounts for most CAH. Untreated classic CAH typically gives unstimulated values of several thousand ng/dL. The 2018 Endocrine Society guideline recommends an early-morning (before 8 a.m.) serum 17-OHP by LC-MS/MS in symptomatic people past infancy, early-follicular sampling in menstruating women, and a cosyntropin stimulation test with an adrenocortical profile for borderline values. It notes that immunoassays remain a source of false positives. Newborn screening uses a dried-blood-spot immunoassay, with LC-MS/MS as a second-tier or confirmation test. Adult reference limits vary widely between LC-MS/MS laboratories (men: ARUP under 139, Mayo and Michigan Medicine under 220 ng/dL), and the luteal rise is large, so phase-specific intervals matter. The guideline advises monitoring treatment with consistently timed samples, relative to the medication schedule and the time of day. Conversion: ng/dL × 0.0303 = nmol/L (molecular weight 330.5).

LOINC 1668-3 (primary), 14569-8, 107495-4. Specimen: serum-or-plasma.

Sources

  1. 17-Hydroxyprogesterone Quantitative by HPLC-MS/MS, Serum or Plasma (test 0092332), ARUP Laboratories
  2. 17-Hydroxyprogesterone (send-out performed by Mayo Clinic Laboratories, test OHPG), UW Medicine Laboratory Test Guide
  3. 17-Hydroxyprogesterone (LC-MS/MS), Michigan Medicine Laboratories (MLabs)
  4. Congenital Adrenal Hyperplasia Due to Steroid 21-Hydroxylase Deficiency: An Endocrine Society Clinical Practice Guideline, Journal of Clinical Endocrinology & Metabolism (2018)
  5. 17-Hydroxyprogesterone (PubChem CID 6238), NCBI PubChem

AI-verified against cited sources. Awaiting expert review. Last reviewed 2026-10-03. How we build and check these pages.

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