Complete Blood Count (CBC) Test
A blood test measuring 17-hydroxyprogesterone levels after GnRH stimulation to evaluate adrenal and gonadal function.
{"Measures hormone levels after GnRH stimulation to check adrenal and pituitary function","Helps diagnose conditions like congenital adrenal hyperplasia (CAH)","Involves taking blood samples at specific time intervals after hormone injection","The 7th specimen is the final sample in a series of tests"}
Key facts at a glance
- LOINC
- 57544-9
- Short code
- 17-OHP GnRH Stim
- Synonyms
- 17OHP sp7 p GnRH SerPl-mCnc
- Category
- chemistry
- Sample
- serum
- Container
- Serum separator tube (SST) or red top serum tube
- Units
- N/A
- Ref low
- 0.8
- Ref high
- 10
- Critical range
- — – 50 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- Chemiluminescence Immunoassay (CLIA) or Enzyme-Linked Immunosorbent Assay (ELISA)
- CPT
- 83498
- SNOMED
- 314196006
- Specimen volume
- 1.0-2.0 mL serum
- Stability
- Refrigerated (2-8°C) for up to 7 days; frozen (-20°C or lower) for longer storage up to 3 months
- Hemolysis max
- 50
- Lipemia max
- 300
- Icterus max
- 20
- TAT
- 24–72 hours
- Order
- routine
A complete blood count, or CBC, is a common blood test that measures the different cells in your blood, including red blood cells, white blood cells, and platelets, giving your healthcare provider a clear picture of your overall health.
The 17-Hydroxyprogesterone (17-OHP) test measures the amount of a hormone called 17-hydroxyprogesterone in your blood. This test is specifically done on the 7th blood sample collected after you receive an injection of Gonadotropin Releasing Hormone (GnRH). This is part of a GnRH stimulation test, which helps doctors understand how your adrenal glands and pituitary gland are working together.
This test is performed to check for a wide range of conditions, such as anemia, infections, and blood disorders. It may be ordered as part of a routine checkup, to investigate symptoms like fatigue, weakness, or fever, or to monitor an ongoing condition or treatment.
The GnRH stimulation test with 17-OHP measurement is primarily used to: (1) Diagnose conditions affecting hormone production, especially congenital adrenal hyperplasia (CAH), (2) Evaluate early or delayed puberty, (3) Assess problems with the adrenal glands or reproductive system, and (4) Distinguish between different types of hormonal disorders. The 7th specimen specifically helps doctors see how your body responds over time to the GnRH stimulation.
The test is done with a simple blood draw. A healthcare provider cleans the skin on the inside of your elbow, wraps a band around your upper arm, and collects a small sample of blood into a tube using a thin needle. The sample is sent to a laboratory for analysis, and the procedure usually takes only a few minutes.
The test involves several steps: First, you will receive a GnRH injection (usually in the arm). Then, blood samples are collected at specific time intervals - typically at 0, 30, 60, and 120 minutes after the injection. The 7th specimen refers to one of these timed samples. A healthcare professional will draw blood from a vein in your arm using a small needle. The samples are then sent to a laboratory for analysis.
Your results show whether your blood cell levels fall within normal ranges. A low red blood cell count may suggest anemia, while a high white blood cell count can point to an infection or inflammation. Abnormal platelet levels may affect blood clotting. Your doctor will interpret the numbers together with your symptoms and medical history to decide if further testing or treatment is needed.
Your doctor will interpret the results based on your age, sex, and clinical symptoms. Elevated 17-OHP levels after GnRH stimulation may indicate conditions such as congenital adrenal hyperplasia, adrenal tumors, or certain ovarian or testicular disorders. Normal levels suggest proper function of the adrenal-gonadal axis. Your healthcare provider will explain what your specific results mean for your health condition.
The risks are very low. You may feel a brief sting or pinch when the needle goes in, and the puncture site may be slightly sore or bruised for a day or two. Serious problems such as infection or excessive bleeding are rare. Tell your provider if you bleed easily or take blood thinners.
The risks of this test are minimal and similar to routine blood tests. You may experience slight pain or bruising at the injection site. Some people might feel lightheaded during or after the blood draw. The GnRH injection may cause temporary symptoms like flushing, headache, or mild nausea. These side effects usually resolve quickly.
Reference range
Reference ranges vary by laboratory and protocol; typically post-GnRH stimulation values are compared to baseline and established cutoffs for assessing adrenal steroidogenesis and gonadal functionN/A
No specific fasting required. Inform patient that this is part of a stimulation test requiring multiple blood draws at specified time intervals after GnRH administration. Document current medications, especially corticosteroids or hormonal therapies.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
The 17-OHP test after GnRH stimulation is crucial for diagnosing congenital adrenal hyperplasia (CAH), a genetic disorder affecting adrenal hormone production. It helps differentiate between various causes of ambiguous genitalia, early puberty, or delayed puberty. The test is also valuable in evaluating adrenal insufficiency, ovarian or testicular tumors, and in assessing pituitary gland function. The timing of the 7th specimen provides important information about how your body responds to hormonal stimulation over time, helping doctors make accurate diagnoses and treatment plans.
Frequently asked questions
Do I need to fast before this test?
How long does the entire test take?
Will I feel any pain during the GnRH injection?
When will I get my results?
Are there any medications I should avoid before the test?
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 10, 2026. · Read our editorial policy