Understanding Your Medical Test: A Complete Patient Guide to Testing, Preparation, and Results

What is this test, and what information does it give my doctor about my health?

The 17-Hydroxyprogesterone (17-OHP) test measures the amount of this hormone in your blood. 17-Hydroxyprogesterone is a substance produced by the adrenal glands that is later converted into cortisol, the body's main stress hormone. This particular test is the 9th blood sample taken after a "challenge" or stimulation test, where you receive an injection of ACTH (adrenocorticotropic hormone) to stimulate your adrenal glands.

How is the test performed, and what are the steps from start to finish?

Before the test, you will receive an injection of synthetic ACTH (cosyntropin) to stimulate your adrenal glands. Blood samples are then taken at specific intervals—typically at baseline (before the injection) and at 30, 60, 90, and 120 minutes after stimulation. The 9th specimen refers to a specific timing in this series. A healthcare professional will draw blood from a vein in your arm, and the sample is sent to a laboratory for analysis.

Why do I need this test, and what conditions can it help detect or monitor?

Your doctor may order this test if you or your child have symptoms suggesting a hormonal disorder, such as early puberty, irregular periods, excessive hair growth, or ambiguous genitalia. It is primarily used to diagnose congenital adrenal hyperplasia (CAH), a genetic condition affecting adrenal hormone production. The test also helps evaluate adrenal gland function and distinguish between adrenal and ovarian or testicular sources of hormone problems.

How should I prepare for the test, including eating, drinking, and taking my medications?

Follow your doctor's instructions carefully. You may need to fast (not eat or drink anything except water) for a certain period before the test. Inform your doctor about all medications you are taking, as some medications can affect hormone levels. Women should tell their doctor about their menstrual cycle timing, as hormone levels can vary throughout the cycle. Wear comfortable clothing with sleeves that can be easily rolled up for blood draw.

What should I expect during the test, and will it be uncomfortable or painful?

You will have an IV line placed or multiple blood draws at scheduled intervals. The ACTH injection may cause temporary flushing, headache, or a rapid heartbeat—this is normal and usually subsides quickly. The series of blood draws may take 2-3 hours total. Bring something to occupy your time, as you will need to remain seated between draws. Tell your nurse immediately if you feel dizzy, nauseated, or experience any unusual symptoms.