Complete Blood Count (CBC): What It Is, How It Is Done, and What Your Results Mean
A blood test that measures 17-hydroxyprogesterone levels 1 hour after receiving corticotropin (ACTH) injection to evaluate adrenal gland function.
{"The test checks how your adrenal glands respond to corticotropin (ACTH) stimulation","It helps diagnose conditions like congenital adrenal hyperplasia (CAH) and adrenal insufficiency","A small blood sample is taken 1 hour after an ACTH injection into the muscle","Results help doctors distinguish between different types of adrenal disorders","The test is usually done in the morning when hormone levels are naturally highest"}
Key facts at a glance
- LOINC
- 14114-3
- Short code
- 17-OHP ACTH stim
- Synonyms
- 17OHP 1h p 250 ug ACTH IM SerPl-mCnc
- Category
- chemistry
- Sample
- serum
- Container
- Serum separator tube (SST/gold top) or plain red top tube
- Units
- N/A
- Ref low
- 1
- Ref high
- 10
- Critical range
- — – 100 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 0–120 years
- Method
- Immunoassay (Chemiluminescence, ELISA, or RIA)
- CPT
- 83498
- SNOMED
- 414589004
- Specimen volume
- 1-2 mL serum minimum
- Stability
- Room temperature: 24 hours; Refrigerated (2-8°C): 7 days; Frozen (-20°C): 30 days. Avoid repeated freeze-thaw cycles.
- Hemolysis max
- 50
- Lipemia max
- 300
- Icterus max
- 20
- TAT
- 24–72 hours
- Order
- routine
What is a complete blood count (CBC)?
The 17-Hydroxyprogesterone (17-OHP) test after ACTH stimulation measures the amount of 17-hydroxyprogesterone in your blood. This test is performed 1 hour after you receive an injection of corticotropin (ACTH, also known as adrenocorticotropic hormone) into your muscle. ACTH normally tells your adrenal glands to produce hormones like cortisol. By measuring 17-OHP levels after this stimulation, doctors can see how well your adrenal glands are working and identify certain disorders.
How is a complete blood count (CBC) performed?
First, a healthcare provider will give you an injection of synthetic corticotropin (ACTH) into a muscle, usually in your arm or thigh. Exactly 1 hour after this injection, a blood sample will be taken from a vein in your arm using a small needle. The sample is then sent to a laboratory for analysis. The entire procedure typically takes about 1-2 hours. You may be asked to fast (not eat or drink anything except water) for a certain period before the test, as directed by your healthcare provider.
Why might I need a complete blood count (CBC)?
Your doctor may order this test if you or your child have symptoms suggesting an adrenal gland problem. Common reasons include: signs of congenital adrenal hyperplasia (CAH), such as early puberty, irregular periods, or ambiguous genitalia in newborns; symptoms of adrenal insufficiency like fatigue, weight loss, low blood pressure, or darkening of the skin; or to differentiate between various adrenal disorders when initial tests show abnormal results.
What do the results of a complete blood count (CBC) mean?
Normal results vary depending on age, sex, and laboratory reference ranges. Elevated 17-OHP levels after ACTH stimulation typically suggest congenital adrenal hyperplasia (CAH), a genetic condition affecting adrenal hormone production. Very high levels may indicate classic CAH, while mildly elevated levels might suggest non-classic CAH. In contrast, people with adrenal insufficiency usually have low or absent cortisol response to ACTH stimulation. Your healthcare provider will interpret your results in the context of your symptoms, medical history, and other test results.
Reference range
Normal response: 17-OHP <10 ng/dL at 60 minutes post ACTH stimulation. Elevated levels >10 ng/dL suggest 21-hydroxylase deficiency (classic CAH). Intermediate values (7-10 ng/dL) may indicate non-classic CAH or carrier status.N/A
Patient should fast overnight (8-12 hours). Baseline sample collected, then 250 ug corticotropin (ACTH) administered intramuscularly. Second sample collected exactly 60 minutes post injection. Inform patient about potential adrenal crisis symptoms. Continue usual medications unless instructed otherwise by physician.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
This test is primarily used to diagnose and differentiate between adrenal gland disorders. It helps confirm or rule out congenital adrenal hyperplasia (CAH), a group of genetic disorders affecting cortisol and androgen production. The test also aids in diagnosing adrenal insufficiency (Addison's disease) and distinguishing between primary adrenal insufficiency (源于肾上腺本身问题) and secondary adrenal insufficiency (源于垂体问题). For newborns with ambiguous genitalia or signs of CAH, this test is crucial for early diagnosis and treatment. Additionally, the test helps monitor treatment effectiveness in patients with CAH and guides medication adjustments.
Frequently asked questions
Are there any risks or side effects?
Do I need to prepare for the test?
How long does it take to get results?
Can this test be done on children?
What happens if my results are abnormal?
Sources
- 1
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- 3
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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