ACTH Stimulation Test (Cosyntropin Stimulation Test) for Evaluating Adrenal Gland Function
This test measures androstenedione levels in your blood 15 minutes after receiving an ACTH injection to evaluate how well your adrenal glands are functioning.
{"Androstenedione is a hormone made by your adrenal glands that serves as a building block for testosterone and estrogen","This test uses an ACTH injection to stimulate your adrenal glands and see how they respond","It helps doctors diagnose conditions like congenital adrenal hyperplasia, adrenal tumors, or polycystic ovary syndrome","Blood is drawn 15 minutes after receiving a 250 mcg corticotropin injection into the muscle","No special fasting is typically required, but follow your doctor's specific instructions"}
Key facts at a glance
- LOINC
- 13856-0
- Short code
- ANDROST15
- Synonyms
- Androst 15M p 250 ug ACTH IM SerPl-mCnc
- Category
- chemistry
- Sample
- serum
- Container
- Red-top serum tube (no anticoagulant) or serum separator tube (SST)
- Units
- N/A
- Ref low
- 0.4
- Ref high
- 2.5
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) or Immunoassay (e.g., RIA, CLIA)
- CPT
- 82157
- SNOMED
- 394871009
- Specimen volume
- 1.0-2.0 mL of serum
- Stability
- Serum stable at room temperature for 8 hours; refrigerated (2-8°C) for 7 days; frozen (-20°C or below) for up to 30 days. Avoid repeated freeze-thaw cycles.
- Hemolysis max
- 100
- Lipemia max
- 200
- Icterus max
- 50
- TAT
- 48–168 hours
- Order
- routine
What is the ACTH stimulation test, and why is it used to check how well your adrenal glands are working?
The Androstenedione test after ACTH stimulation measures the level of androstenedione in your blood. Androstenedione is a steroid hormone produced mainly by your adrenal glands (small glands sitting on top of your kidneys) and, in smaller amounts, by your ovaries. It acts as a precursor, meaning your body converts it into other important hormones like testosterone and estrogen.
How does the ACTH stimulation test work, and what role does the hormone ACTH play in triggering cortisol production in your body?
ACTH (adrenocorticotropic hormone), also called corticotropin, is a hormone that tells your adrenal glands to produce more hormones. During this test, you will receive a small injection of synthetic ACTH (250 mcg) into a muscle. Fifteen minutes later, a blood sample will be taken to measure how much androstenedione your adrenal glands produced in response to this stimulation. This helps doctors understand if your adrenal glands are working properly.
Why might I need the ACTH stimulation test, and which symptoms of adrenal insufficiency could prompt my doctor to order it?
Your doctor may order this test if you have symptoms of excess androgens (male hormones), such as abnormal hair growth, acne, or irregular periods in women. It can also help determine if symptoms are coming from your adrenal glands or your ovaries. Additionally, this test is useful for evaluating adrenal gland function and diagnosing conditions like congenital adrenal hyperplasia or adrenal tumors.
How should I prepare for the ACTH stimulation test, including which medicines I may need to pause and whether fasting is required?
Follow your doctor's instructions carefully. You may need to stop taking certain medications, especially hormone supplements or steroids, before the test. Fasting may or may not be required—your healthcare provider will let you know. Be sure to inform your doctor about all medications and supplements you are taking.
What happens during the ACTH stimulation test, from the first blood draw through the injections and the samples taken afterward?
A healthcare professional will give you an injection of synthetic ACTH into a muscle (usually in your arm or buttock). Exactly 15 minutes after the injection, they will draw a blood sample from a vein in your arm. The blood sample will be sent to a laboratory for analysis. The entire procedure usually takes about 30 minutes.
Are there any risks or side effects associated with the ACTH stimulation test that I should discuss with my healthcare team beforehand?
The risks are minimal and similar to any blood test. You may experience slight pain or bruising at the injection site. Some people might feel a brief flutter or warmth after the ACTH injection. Serious side effects are rare but can include allergic reactions. Contact your healthcare provider if you experience unusual symptoms.
Reference range
Post-ACTH stimulation reference values are interpreted as a stimulated response. Baseline androstenedione levels in adult males: 0.4-2.5 ng/mL; adult females: 0.3-3.5 ng/mL. Post-stimulation (250 ug cosyntropin IM) levels should increase appropriately, generally doubling or more from baseline in cases of intact adrenal steroidogenesis.N/A
No special fasting required. Test is typically performed in the morning. Patient should be in a rested state. ACTH (cosyntropin) 250 ug is administered intramuscularly as a stimulation agent; specimen collected 15 minutes post-injection. Certain medications (e.g., corticosteroids, oral contraceptives, ketoconazole) may affect results and should be noted.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
This test is primarily used to evaluate adrenal gland function and differentiate between adrenal and ovarian sources of excess hormone production. Elevated androstenedione levels after ACTH stimulation may indicate conditions such as congenital adrenal hyperplasia (a genetic disorder affecting hormone production), adrenal tumors, or polycystic ovary syndrome (PCOS). Abnormally low response might suggest adrenal insufficiency (Addison's disease) or hypopituitarism. The results help doctors make accurate diagnoses and guide appropriate treatment plans.
Frequently asked questions
Will I need to fast before this test?
How long does it take to get results?
Can I take my regular medications before the test?
Is this test safe during pregnancy?
What do abnormal results mean?
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 15, 2026. · Read our editorial policy