Understanding Your Medical Test: What It Is, How It Is Done, and What Your Results Mean
A blood test that measures 17-hydroxyprogesterone levels 1.5 hours after a hormone stimulation challenge to evaluate adrenal gland function.
{"Measures how your adrenal glands respond to stimulation","Helps diagnose conditions like congenital adrenal hyperplasia (CAH)","Involves a blood draw before and after a hormonal challenge","Results help doctors distinguish between different adrenal disorders","The challenge test typically uses ACTH (adrenocorticotropic hormone)"}
Key facts at a glance
- LOINC
- 56616-6
- Short code
- 17OHP-ACT stim
- Synonyms
- 17OHP 1.5h 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
- 10
- Ref high
- 30
- Critical range
- 2 N/A – 100 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- ≥ 0 years
- Method
- Chemiluminescent Immunoassay (CLIA) or Enzyme-Linked Immunosorbent Assay (ELISA)
- CPT
- 82533
- SNOMED
- 31322003
- 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. Avoid repeated freeze-thaw cycles.
- Hemolysis max
- 50
- Lipemia max
- 60
- Icterus max
- 40
- TAT
- 24–72 hours
- Order
- routine
What is this test? This test is a medical evaluation that helps your healthcare provider gather important information about your health, look for signs of illness, and guide decisions about your ongoing care.
The 17-Hydroxyprogesterone (17-OHP) test measures the level of 17-hydroxyprogesterone in your blood. This hormone is produced by the adrenal glands, which are small glands located on top of your kidneys. The '1.5 hours post challenge' means the blood sample is taken 1.5 hours after you receive a hormonal substance (typically ACTH) that stimulates your adrenal glands to produce more hormones.
How is the test performed? A trained member of your care team will perform the test, explain each step before starting, follow careful safety procedures, and do everything possible to keep you comfortable throughout the process.
The test involves two blood draws: 1) A baseline sample taken before the challenge, and 2) A second sample taken 1.5 hours after receiving an injection of ACTH (adrenocorticotropic hormone). This 'challenge' or 'stimulation' test helps doctors see how well your adrenal glands respond to stress or stimulation. The procedure is similar to other blood tests—a healthcare professional will draw blood from a vein in your arm.
Why might I need this test? You may need this test because your doctor wants to check for a possible health problem, confirm or rule out a diagnosis, monitor a condition you already have, or see how well a current treatment is working.
Your doctor may order this test if you or your child show signs of a hormonal disorder, particularly to help diagnose congenital adrenal hyperplasia (CAH). CAH is a genetic condition that affects the adrenal glands' ability to produce cortisol and sometimes aldosterone. The test may also be used to evaluate adrenal insufficiency or distinguish between different types of adrenal disorders.
What do the results mean? Your results show whether your findings fall within the range expected for someone of your age and overall health. Your doctor will review them with you, explain what they mean, and discuss any next steps in your care.
Results are interpreted based on whether the 17-OHP level rises appropriately after the ACTH challenge. A normal response shows a significant increase in 17-OHP levels. Abnormally high levels after stimulation may indicate congenital adrenal hyperplasia or other adrenal disorders. Your doctor will compare your results to established reference ranges and consider your symptoms and medical history when making a diagnosis.
Are there any risks? Most people tolerate this test very well, but like many medical procedures it can carry some risks, such as mild discomfort, bruising, or rarely bleeding or infection. Your care team will discuss any concerns with you beforehand.
The risks are minimal and similar to routine blood tests, including slight bruising, bleeding, or dizziness at the injection site. The ACTH stimulation itself is generally well-tolerated but may cause temporary flushing, headache, or mild nausea. Serious side effects are rare. Your healthcare provider will monitor you during the test.
Reference range
Reference range varies by laboratory and assay methodology. Post-ACTH stimulation (1.5 hours): typically >10-15 ng/dL indicates normal adrenal response; >30 ng/dL suggests possible congenital adrenal hyperplasia (CAH); >100 ng/dL strongly suggestive of 21-hydroxylase deficiency. Interpret in clinical context.N/A
Patient should fast overnight (8-12 hours). Baseline sample collected, then synthetic ACTH (cosyntropin) administered intravenously or intramuscularly. Second sample collected 1.5 hours post-administration. Inform patient of potential mild side effects from ACTH including facial flushing, nausea, or headache. Continue any prescribed medications unless instructed otherwise by physician.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
The 17-OHP stimulation test is primarily used to diagnose and differentiate forms of congenital adrenal hyperplasia (CAH), particularly the classic 21-hydroxylase deficiency form. It helps distinguish between CAH and other conditions that may cause similar symptoms, such as adrenal tumors or androgen-secreting disorders. The test is also valuable for evaluating adrenal gland function and detecting partial enzyme deficiencies. Early diagnosis of CAH is important for proper treatment and management.
Frequently asked questions
Do I need to fast before this test?
How long does the entire test take?
Can children undergo this test?
What happens after the test?
Are there medications that can affect the results?
Sources
- 1
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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