17-OH Progesterone: Purpose, Levels, and Meaning

What Is 17-OH Progesterone?

17-hydroxyprogesterone (17-OH progesterone or 17-OHP) is a hormone made mostly by the adrenal glands, and in smaller amounts by the ovaries or testes. It helps the body make other important hormones like cortisol (which controls stress and blood sugar) and androgens (male sex hormones).

If the body has a problem making cortisol, usually due to a missing enzyme (a protein that speeds things up), 17-OHP builds up in the blood. This is a key sign of a condition called Congenital Adrenal Hyperplasia (CAH).

What Is 17-OH Progesterone Used For?

Doctors use 17-OH progesterone testing to:

• Diagnose CAH, especially in newborns
• Check for milder forms of CAH in children or adults with symptoms like early puberty or irregular periods
• Monitor treatment in people who already have CAH

This test helps doctors understand how well your adrenal glands are working and whether your hormone levels are in balance.

When Is 17-OH Progesterone Testing Recommended?

17-OH progesterone testing is not part of routine health checkups. It’s usually ordered when doctors suspect a hormone imbalance, especially related to the adrenal glands.

You may need this test if:

• A newborn shows signs of CAH, such as vomiting, dehydration, or unusual genital development
• A child has early signs of puberty
• An adult has symptoms like irregular periods, excess body hair, or fertility problems
• A baby boy has an unusually small penis or other genital differences
• You have already been diagnosed with CAH, and your doctor wants to monitor your treatment
• A family history of CAH exists, and testing is needed to screen or confirm the condition

This test helps catch problems early and guides the right treatment to balance hormone levels.

How Is 17-OH Progesterone Testing Conducted?

The 17-OH progesterone test is usually done with a blood test. For newborns, it’s often part of the routine heel-prick screening done a few days after birth. For older children or adults, a blood sample is taken from a vein in the arm.

In some cases, especially when results are unclear, doctors may order an ACTH stimulation test. This involves giving a small amount of synthetic ACTH (a hormone that stimulates the adrenal glands) and checking how 17-OHP levels respond. It helps confirm or rule out mild or nonclassic CAH.

Is It Part of a Standard Panel?

No, 17-OH progesterone is not included in common panels like CMP. It is a specialized hormone test ordered for specific concerns. The doctor may order it as part of a hormonal panel.

Do You Need to Prepare for the Test?

Yes, some preparation may be needed:

• Fasting is not usually required, but follow your doctor’s instructions
• Women may need to have the test at a certain time in their menstrual cycle for accurate results
• Tell your doctor if you take any steroid medications, as they can affect the test

Getting accurate results depends on proper timing and preparation, so always follow your healthcare provider’s advice.

What Are the Normal 17-OH Progesterone Levels?

Normal levels of 17-OH progesterone depend on your age, sex, and whether you're pregnant. So, results should always be interpreted by a healthcare provider.

Here are general reference ranges for blood tests:

• Newborns (screening): Less than 630 ng/dL
• Children before puberty:  Around 100 ng/dL
• Adults:  Less than 200 ng/dL

“In practice, many doctors consider 100-150 ng/dL to be a normal range for men”, says a gynecologist.

In females, levels can vary depending on the menstrual phase: typically below 80 ng/dL in the follicular phase, up to 285 ng/dL in the luteal phase, and significantly higher during pregnancy.

Note: The units of measurement and the normal ranges can differ depending on the laboratory and the specific methods used. Always review your results with a doctor.

What Do Abnormal 17-OH Progesterone Levels Mean?

Abnormal levels of 17-OH progesterone usually point to a problem in how the body makes hormones like cortisol or androgens. In most cases, high levels are more common and more concerning than low ones.

17-OH Progesterone High Levels

When 17-OH progesterone is too high, it often means the body is missing an enzyme (usually 21-hydroxylase) that helps convert it into cortisol. This leads to a buildup of 17-OHP in the blood.

Common causes include:

• Congenital Adrenal Hyperplasia (CAH): A genetic condition where enzyme deficiency causes hormone imbalance. In classic CAH, symptoms start at birth or shortly after.
• Nonclassic CAH: A milder form that appears later in life. It can cause early puberty, acne, irregular periods, or excess body hair.
• Adrenal tumors or hyperplasia: In rare cases, abnormal growths on the adrenal glands can raise hormone levels.

To manage high 17-OH progesterone levels:

• Follow your doctor’s treatment plan, which may include hormone therapy.  (like glucocorticoids).
• Attend regular check-ups to monitor hormone levels and adjust treatment as needed.
• Inform your healthcare provider if symptoms like irregular periods, fatigue, or early puberty appear or worsen.
• Consider genetic counseling if CAH runs in your family or you plan to have children.

17-OH Progesterone Low Levels

Low levels of 17-OH progesterone are less common and usually not a cause for concern on their own. However, in some cases, they may signal underactive adrenal glands or other hormone-related conditions.

Possible causes include:

• Adrenal insufficiency: The adrenal glands are not making enough hormones, including cortisol and androgens.
• Certain genetic conditions: Rare enzyme defects other than CAH may lead to low 17-OHP levels.
• Overtreatment of CAH: In people receiving hormone therapy, levels may drop too low if the medication dose is too high.

To manage low 17-OH progesterone levels:

• Work closely with your doctor to understand if treatment adjustments are needed.
• Report new symptoms like fatigue, dizziness, or low blood pressure, which may suggest hormone imbalance.
• Regular monitoring can help keep levels within the healthy range and avoid complications.

Which Specialist Should You Consult?

If your 17-OH progesterone levels are abnormal, the right specialist can help you understand the cause and create a treatment plan. The type of doctor you need may depend on your symptoms and age.

You may be referred to:

• Endocrinologist - A hormone specialist who can diagnose and treat conditions like CAH, adrenal disorders, and hormonal imbalances.
• Pediatric endocrinologist - If the patient is a child or teenager, this specialist can manage growth, puberty, and adrenal conditions.
• Gynecologist - For women with irregular periods, excess body hair, or fertility issues related to hormone levels.
• Genetic counselor - If CAH runs in your family, a counselor can help assess your risk or discuss testing options.