Complete Blood Count (CBC)
A blood test measuring 17-hydroxyprogesterone levels after gonadotropin releasing hormone (GnRH) stimulation to evaluate adrenal gland function.
{"This test measures 17-OHP hormone levels in blood after GnRH stimulation","It helps diagnose adrenal gland disorders like congenital adrenal hyperplasia","The test involves drawing multiple blood samples after receiving GnRH","Results help doctors distinguish between different adrenal conditions"}
Key facts at a glance
- LOINC
- 57541-5
- Short code
- 17-OHP GnRH stim 4
- Synonyms
- 17OHP sp4 p GnRH SerPl-mCnc
- Category
- chemistry
- Sample
- serum
- Container
- Serum Separator Tube (SST) or Plain Red Top Tube
- Units
- N/A
- Ref low
- 50
- Ref high
- 200
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 0–18 years
- Method
- Chemiluminescent Immunoassay (CLIA)
- CPT
- 83498
- SNOMED
- 314160006
- Specimen volume
- 1.0-2.0 mL serum minimum
- Stability
- Room temperature: 24 hours; Refrigerated (2-8°C): 7 days; Frozen (-20°C or below): 30 days
- Hemolysis max
- 50
- Lipemia max
- 300
- Icterus max
- 20
- TAT
- 24–72 hours
- Order
- routine
A complete blood count (CBC) is a common blood test that measures the different cells in your blood, including red blood cells, white blood cells, and platelets, and is often used to evaluate your overall health.
The 17-Hydroxyprogesterone (17-OHP) test measures the amount of a hormone called 17-hydroxyprogesterone in your blood. This hormone is produced by your adrenal glands, which sit on top of your kidneys. This specific test is called the '4th specimen post dose GnRH' test, which means blood samples are taken at specific intervals after you receive a dose of gonadotropin releasing hormone (GnRH) to see how your adrenal glands respond.
Your doctor may order this test as part of a routine checkup, to look into symptoms such as fatigue, weakness, fever, or unexplained bruising, or to monitor an ongoing medical condition or the effects of treatment.
Your doctor may order this test if they suspect you have a disorder of the adrenal glands. The most common reason is to check for congenital adrenal hyperplasia (CAH), a genetic condition that affects how the adrenal glands produce hormones. This test may also be used to evaluate early puberty in children, irregular menstrual periods in women, or other hormonal imbalances.
A healthcare professional will draw a small sample of blood from a vein, usually on the inside of your elbow. The procedure takes only a few minutes, and you can normally return to your regular activities right afterward.
First, you will receive an injection of GnRH, which is a hormone that stimulates your pituitary gland. Then, your healthcare provider will draw blood samples at specific time intervals - typically at 0, 30, 60, and 120 minutes after the injection. The '4th specimen' refers to the sample taken at the final time point. The blood samples are sent to a laboratory where the 17-OHP levels are measured.
Values that fall outside the typical ranges may point to conditions such as anemia, infection, inflammation, or clotting problems, but your doctor will interpret your results together with your symptoms and medical history.
Normal results vary based on age, sex, and menstrual cycle phase. Elevated 17-OHP levels after GnRH stimulation may indicate congenital adrenal hyperplasia or other adrenal disorders. Your doctor will interpret your results in the context of your symptoms and other test results.
Reference range
Reference range varies based on pubertal stage and timing post-GnRH stimulation. Peak 17-OHP levels after GnRH stimulation typically range from 50-200 ng/dL in normal prepubertal children. Clinical interpretation should be based on age and sex-specific reference ranges established by the testing laboratory.N/A
No fasting required. This is the 4th specimen collected following gonadotropin releasing hormone (GnRH) or GnRH agonist administration as part of a stimulation test. Patient should remain at rest during the collection period. Inform the laboratory of any medications, particularly glucocorticoids or hormonal therapies, that may affect results.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
This test is primarily used to diagnose and differentiate adrenal gland disorders. Elevated 17-OHP levels after GnRH stimulation suggest adrenal hyperplasia, while a minimal response may indicate other pituitary or adrenal issues. The test helps distinguish between various causes of hormonal imbalances, including congenital adrenal hyperplasia, adrenal tumors, and pituitary disorders. Early detection of these conditions allows for appropriate treatment and management.
Frequently asked questions
Is the GnRH injection safe?
How long does the entire test take?
Do I need to fast before this test?
Are there any medications that affect the results?
Sources
- 1
- 2
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 10, 2026. · Read our editorial policy