Understanding Your Medical Test: What It Is and How to Prepare
A blood test measuring 17-hydroxyprogesterone levels after GnRH stimulation to evaluate adrenal gland function and screen for congenital adrenal hyperplasia.
{"17-OHP is a hormone produced by the adrenal glands","This test helps diagnose congenital adrenal hyperplasia (CAH)","Blood samples are taken before and after GnRH injection","Elevated levels may indicate adrenal gland problems","The test requires multiple blood draws over several hours"}
Key facts at a glance
- LOINC
- 57539-9
- Short code
- 17-OHP GnRH stim
- Synonyms
- 17OHP sp2 p GnRH SerPl-mCnc
- Category
- chemistry
- Sample
- serum
- Container
- Serum Separator Tube (SST) or Plain Red Top Tube
- Units
- N/A
- Ref low
- 2
- Ref high
- 5
- Critical range
- — – 10000 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 0–100 years
- Method
- Immunoassay (Chemiluminescence Immunoassay or ELISA)
- CPT
- 82533
- SNOMED
- 31318003
- Specimen volume
- 1-2 mL serum
- Stability
- Room temperature: 8 hours; Refrigerated (2-8°C): 24 hours; Frozen (-20°C): 7 days. Avoid repeated freeze-thaw cycles.
- Hemolysis max
- 50
- Lipemia max
- 300
- Icterus max
- 20
- TAT
- 24–72 hours
- Order
- routine
This test is a medical procedure that helps your doctor measure specific substances or functions in your body. The results provide important information about your overall health and can help identify conditions that may need further evaluation, monitoring, or treatment.
The 17-Hydroxyprogesterone (17-OHP) test measures the amount of 17-hydroxyprogesterone in your blood. 17-OHP is a hormone produced by the adrenal glands, which sit on top of your kidneys. This particular test is performed after receiving a gonadotropin releasing hormone (GnRH) injection, which stimulates the body to produce additional hormones. This 'stimulation test' helps doctors see how well your adrenal glands and pituitary gland are working together.
Your doctor has ordered this test to help diagnose or monitor a health condition, to check how well a current treatment is working, or to screen for potential problems before symptoms appear. The results give your care team the information needed to make confident decisions about your ongoing care.
Your doctor may order this test if they suspect you have a condition affecting your adrenal glands, such as congenital adrenal hyperplasia (CAH). CAH is a genetic disorder that affects the adrenal glands' ability to produce certain hormones. The test may also be used to evaluate early or delayed puberty, infertility issues, or abnormal hormone levels. The GnRH stimulation helps reveal problems that might not be visible in a baseline test.
The test is usually performed by a trained health care professional in a clinic, laboratory, or hospital. A small sample, such as blood or urine, may be collected, or a specialized instrument may be used. The procedure is typically quick, and most patients are able to return home the same day.
A healthcare provider will first draw a baseline blood sample. Then, you will receive an injection of GnRH (usually into a muscle or under the skin). Additional blood samples will be taken at specific time intervals—typically 15, 30, 45, and 60 minutes after the injection. These multiple samples help track how your body responds to the hormone stimulation. The entire procedure usually takes about 1-2 hours.
Your care team will give you specific instructions before the test. You may need to fast for several hours, avoid certain foods or medications, or drink extra water beforehand. Tell your doctor about all medicines and supplements you take, and ask questions if anything is unclear.
Your doctor will provide specific instructions. 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 medicines can affect hormone levels. Women should tell their doctor if they are having their period, as hormone levels can vary throughout the menstrual cycle. Wear comfortable clothing with sleeves that can be easily rolled up for the blood draws.
Most patients experience no serious problems from this test. If a blood sample is taken, you may feel slight pain, bruising, or bleeding at the needle site, and infection is rare. Serious complications are uncommon, but contact your doctor if you notice unusual swelling, persistent bleeding, or fever.
The risks are minimal and similar to routine blood tests. You may experience slight pain or bruising at the injection site. Some people might feel dizzy or lightheaded during or after the blood draw. The GnRH injection may cause temporary flushing, headache, or mild nausea. These side effects usually resolve quickly. Serious complications are rare.
Reference range
For GnRH-stimulated 17-OHP: Peak response typically 2-5 times baseline. Reference range varies by laboratory protocol and assay method. Consult assay-specific reference ranges.N/A
No fasting required. Patient should follow standard GnRH stimulation test protocol: baseline sample collected, GnRH administered, then 2nd specimen collected 60-120 minutes post-dose. Avoid glucocorticoids and hormonal contraceptives prior to testing as they may affect results. Inform physician of current medications.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Elevated 17-OHP levels after GnRH stimulation typically indicate congenital adrenal hyperplasia (CAH), a group of genetic disorders affecting adrenal hormone production. The most common form is 21-hydroxylase deficiency. In severe cases, CAH can cause ambiguous genitalia in newborns, early puberty, rapid growth followed by short stature, and fertility problems. The GnRH stimulation test helps distinguish between different types of hormonal disorders and can identify milder forms of CAH that might not be detected with a single baseline test. Results are interpreted alongside other hormone tests and clinical symptoms to confirm diagnosis and guide treatment.
Frequently asked questions
How long does it take to get results?
Does the GnRH injection have any long-term effects?
Can children have this test?
What happens if my results are abnormal?
Sources
- 1
- 2
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 14, 2026. · Read our editorial policy