17-Hydroxyprogesterone (17-OHP) – Serum Test

What It Is:
17-Hydroxyprogesterone (17-OHP) is a steroid hormone produced in the adrenal glands and gonads. It is a precursor in the biosynthesis of cortisol and androgens.

Purpose of the Test:
The 17-OHP serum test is primarily used to help diagnose and monitor congenital adrenal hyperplasia (CAH)—especially 21-hydroxylase deficiency, the most common form. It may also be used to investigate adrenal or ovarian tumors, or ambiguous genitalia in newborns.

Sample Type:

Serum (collected via a blood sample, usually drawn from a vein).

Why It Matters:

In CAH, the enzyme defect causes decreased cortisol and/or aldosterone, leading to a buildup of 17-OHP.

Elevated levels may also be seen in adrenal tumors, polycystic ovary syndrome (PCOS), and stress.

Low levels are generally not of clinical concern unless part of a broader endocrine disorder.

Normal Range:

Reference values vary by age, sex, and time of day, but are typically lower in healthy individuals.

Newborn screening has specific cut-off values due to naturally high levels at birth.

Timing Consideration:

In adults, samples are usually drawn in the morning due to diurnal hormone variation.