Complete Blood Count (CBC) Test: What You Need to Know
A blood test that measures 17-hydroxyprogesterone levels 30 minutes after corticotropin (ACTH) injection to help diagnose adrenal gland disorders.
{"Measures how your adrenal glands respond to ACTH hormone stimulation","Primarily used to diagnose and differentiate types of congenital adrenal hyperplasia (CAH)","Helps distinguish between adrenal and gonadal causes of hormone excess","Involves two blood draws: one before and one 30 minutes after ACTH injection","Results help your doctor determine if adrenal enzyme deficiencies are present"}
Key facts at a glance
- LOINC
- 101311-9
- Short code
- 17-OHP ACTH stim
- Synonyms
- 17OHP 30M p ACTH SerPl-mCnc
- Category
- chemistry
- Sample
- serum
- Container
- Serum separator tube (SST) or plain red top tube
- Units
- N/A
- Ref low
- 10
- Ref high
- 20
- Critical range
- — – 100 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 0–120 years
- Method
- Immunoassay (Chemiluminescence or ELISA)
- CPT
- 82533
- SNOMED
- 31309004
- Specimen volume
- 1-2 mL serum
- Stability
- Room temperature: 24 hours; Refrigerated (2-8°C): 7 days; Frozen (-20°C or below): 30 days. Protect from light.
- Hemolysis max
- 50
- Lipemia max
- 100
- 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 doctor a clear picture of your overall health and how well your body is working.
The 17-Hydroxyprogesterone (17-OHP) after ACTH stimulation test measures the level of 17-OHP in your blood before and 30 minutes after receiving an injection of corticotropin (ACTH). ACTH is a hormone produced by the pituitary gland that tells your adrenal glands to produce hormones like cortisol and 17-OHP. This test evaluates how well your adrenal glands respond to ACTH stimulation.
Your doctor may order this test as part of a routine checkup, to look into symptoms such as fatigue, weakness, fever, or unusual bruising, to monitor an ongoing condition such as anemia or infection, or to see how a treatment like chemotherapy is affecting your blood cells.
Your doctor may order this test if you have symptoms suggesting congenital adrenal hyperplasia (CAH), a group of genetic disorders affecting adrenal hormone production. It may also be used to evaluate ambiguous genitalia in infants, early puberty in children, excess hair growth (hirsutism) in women, or adrenal masses. The test helps determine whether a hormone problem originates from the adrenal glands or the ovaries/testes.
Most people do not need special preparation for a CBC, and you can usually eat and drink normally beforehand. If your blood sample will also be used for tests that require fasting, such as a glucose test, your doctor will tell you not to eat or drink anything except water for a set period of time before the blood draw.
Follow your doctor's instructions regarding fasting and medication adjustments. Certain medications, especially corticosteroids and hormonal treatments, may affect results. Inform your doctor about all medications and supplements you take. The test is typically performed in the morning, as hormone levels naturally vary throughout the day.
During the test, a health care professional will wrap a band around your upper arm, clean the skin on the inside of your elbow with an antiseptic, and insert a small needle into a vein to collect a blood sample into one or more tubes. The draw usually takes only a few minutes, and then a small bandage is placed on the site.
A healthcare professional will first draw a baseline blood sample. Then, synthetic ACTH (cosyntropin) will be injected into your muscle or vein. After exactly 30 minutes, another blood sample will be drawn. The procedure takes about 45-60 minutes total. You may experience mild discomfort from the needle insertion.
Your results will show whether your red blood cells, white blood cells, and platelets fall within the normal ranges on your report. Values that are too high or too low can point to conditions such as anemia, infection, inflammation, or clotting problems, but many factors can affect the numbers. Your doctor will review the full panel along with your symptoms and history to explain what your results mean and whether any follow-up is needed.
Normal 17-OHP response to ACTH stimulation varies by age and sex. A significantly elevated 17-OHP level after stimulation suggests classic congenital adrenal hyperplasia. Mild to moderate elevations may indicate non-classic CAH or other adrenal disorders. Your doctor will interpret your results in context with your symptoms, age, and other test findings.
A CBC is very safe. You may feel a brief sting when the needle goes in, and the puncture site can be slightly sore, bruised, or red for a day or two. Serious problems, such as heavy bleeding or infection at the draw site, are rare, and the small amount of blood taken will not affect your health. Tell your care team if you have felt faint during blood draws before or have a bleeding disorder.
Risks are minimal and include minor bleeding, bruising, or infection at the injection site. Some people may experience temporary flushing, headache, or dizziness from the ACTH injection. Serious allergic reactions to ACTH are rare but possible.
Reference range
Reference range varies by age and clinical context. For post-ACTH stimulation: Normal response typically <10 ng/dL (0.3 nmol/L). Intermediate/gray zone: 10-20 ng/dL (0.3-0.6 nmol/L). Elevated suggestive of 21-hydroxylase deficiency: >20 ng/dL (>0.6 nmol/L). Classic CAH typically shows marked elevations >100 ng/dL.N/A
Patient should be at rest. Corticotropin (ACTH 1-24) is administered intravenously or intramuscularly at standard dose (250 mcg for adults, weight-based for children). Blood sample is collected exactly 30 minutes post-ACTH administration. No fasting required. Inform patient of potential for mild flushing or dizziness following ACTH administration.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Frequently asked questions
How long does it take to get results?
Do I need to fast before this test?
Can this test be done during pregnancy?
What happens if I can't have the ACTH injection?
Will I need to repeat this test?
Sources
- 1
- 2
- 3
- 4
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