Understanding Your Medical Lab Test: A Patient's Guide to Testing, Preparation, and Results
A blood test measuring 17-hydroxyprogesterone levels 4 hours after ACTH stimulation to help diagnose adrenal gland disorders.
{"Measures hormone levels to check for adrenal gland problems","Part of an ACTH stimulation test to diagnose conditions like congenital adrenal hyperplasia (CAH)","Involves blood sample collection 4 hours after a hormonal challenge","Results help doctors evaluate adrenal gland function","May require fasting and medication adjustments before testing"}
Key facts at a glance
- LOINC
- 57003-6
- Short code
- 17-OHP-4HR
- Synonyms
- 17OHP 4h p chal SerPl-mCnc
- Category
- chemistry
- Sample
- serum
- Container
- Serum separator tube (SST/gold top) or plain red top tube
- Units
- N/A
- Ref low
- 0.2
- Ref high
- 3
- Critical range
- — – 1000 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- ≥ 0 years
- Method
- Chemiluminescence immunoassay (CLIA) or Liquid chromatography-tandem mass spectrometry (LC-MS/MS)
- CPT
- 83498
- SNOMED
- 31318009
- Specimen volume
- 1-2 mL serum
- Stability
- Room temperature: 24 hours; Refrigerated (2-8°C): 7 days; Frozen (-20°C or below): 30 days. Avoid repeated freeze-thaw cycles.
- Hemolysis max
- 50
- Lipemia max
- 300
- Icterus max
- 20
- TAT
- 24–72 hours
- Order
- routine
What is this test? This test is a laboratory procedure that measures specific substances in your body, helping your healthcare provider evaluate your overall health, screen for certain conditions, or monitor how well a treatment plan is working.
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. The test is performed 4 hours after receiving an ACTH (adrenocorticotropic hormone) injection, which stimulates your adrenal glands to produce hormones. This is called an ACTH stimulation test or challenge test.
Why do I need this test? Your doctor may order this test to find the cause of symptoms you are experiencing, check how well your organs are functioning, screen for diseases before they cause problems, or see whether your current treatment is effective.
Your doctor may order this test if they suspect you have a disorder affecting your adrenal glands, particularly congenital adrenal hyperplasia (CAH). CAH is a genetic condition that affects the adrenal glands' ability to produce cortisol and sometimes aldosterone. The test helps doctors see how your adrenal glands respond to stimulation and whether they are functioning properly.
How should I prepare? Preparation depends on the type of test being performed. You may be asked to fast for 8 to 12 hours, avoid certain foods, drinks, or medications, or drink extra water beforehand. Always follow the specific instructions from your healthcare provider and mention any medicines or supplements you take.
Follow your doctor's instructions carefully. You may need to fast (not eat or drink) for a certain period before the test. Certain medications, especially steroids or hormone treatments, may need to be stopped before testing. Inform your doctor about all medications, supplements, or herbal products you are taking. The test involves an initial blood draw, followed by an ACTH injection, and another blood draw 4 hours later.
What happens during the test? For most laboratory tests, a trained professional draws a small sample of blood from a vein in your arm, collects a urine sample, or performs a quick, painless scan. The procedure usually takes only a few minutes, and the sample is then sent to a laboratory for analysis.
A healthcare professional will first draw a blood sample from a vein in your arm. Then, you will receive an injection of ACTH. After exactly 4 hours, another blood sample will be drawn. The entire process takes about 4-5 hours. You may be asked to rest in the clinic during this waiting period.
Are there any risks? These tests are very safe. You may feel a brief sting during a blood draw and notice slight bruising afterward, but serious complications such as infection or excessive bleeding are rare. Contact your provider if you have unusual pain, swelling, or bleeding that does not stop.
The risks are minimal and similar to routine blood tests. You may experience slight pain, bruising, or bleeding at the injection site. Some people may feel lightheaded after having blood drawn. The ACTH injection may cause temporary flushing, headache, or nausea. These side effects usually resolve quickly.
Reference range
Post-ACTH stimulation: 17-Hydroxyprogesterone typically rises significantly. Reference range varies by laboratory method. For CAH confirmation: Stimulated 17-OHP >1000 ng/dL (30 nmol/L) suggests classic 21-hydroxylase deficiency. Baseline: 0.2-3.0 ng/mL; Post-stimulation: <10 ng/mL (normal), 10-100 ng/mL (heterozygote/carrier), >100 ng/mL (classic CAH).N/A
No fasting required. Patient should be informed that this is an ACTH (cosyntropin) stimulation test. Baseline sample is drawn, then synthetic ACTH is administered intramuscularly or intravenously, followed by a second blood draw 4 hours later. Avoid corticosteroid medications prior to testing if clinically feasible. Inform patient about the two-sample collection protocol.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
This test is primarily used to diagnose and monitor congenital adrenal hyperplasia (CAH), a group of genetic disorders affecting adrenal hormone production. In CAH, the adrenal glands produce too little cortisol and may produce excess androgens (male hormones). Elevated 17-OHP levels after ACTH stimulation typically indicate CAH. The test can also help distinguish between different types of adrenal disorders and evaluate adrenal gland function. Results are interpreted alongside other hormone tests and clinical symptoms.
Frequently asked questions
How long does it take to get results?
What do abnormal results mean?
Do I need to do anything special after the test?
Can children have this test?
Sources
- 1
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- 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