Understanding Your Laboratory Test: What It Is, How It Works, and How to Prepare
This test measures corticotropin (ACTH) levels in blood 2.5 hours after receiving a glucagon injection to evaluate adrenal gland function.
{"Measures ACTH hormone levels after glucagon stimulation","Helps diagnose adrenal gland disorders like Cushing's disease","Involves a blood draw before and after glucagon injection","Requires fasting overnight before the test","Results help doctors assess if adrenal glands respond properly"}
Key facts at a glance
- LOINC
- 58564-6
- Short code
- ACTH post-glucagon
- Synonyms
- ACTH 2.5h p Gc Plas-sCnc
- Category
- chemistry
- Sample
- plasma
- Container
- EDTA plasma tube (Lavender top) - Polypropylene or siliconized collection tubes recommended to prevent adsorption of ACTH to glass surfaces.
- 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
- ≥ 18 years
- Method
- Chemiluminescent Immunoassay (CLIA) or Radioimmunoassay (RIA)
- CPT
- 82024
- SNOMED
- 313295008
- Specimen volume
- 1-2 mL of plasma minimum, 2.5 mL preferred for duplicate testing
- Stability
- ACTH is highly unstable in vitro. Sample should be collected on ice, plasma separated immediately via centrifugation at 2-8°C, and frozen at -20°C or lower within 30-60 minutes of collection. Stable for up to 3 months at -70°C. Avoid repeated freeze-thaw cycles.
- Hemolysis max
- 50
- Lipemia max
- 300
- Icterus max
- 40
- TAT
- 24–72 hours
- Order
- routine
What is this test, and why has my doctor ordered it for me?
The ACTH stimulation test with glucagon measures the level of corticotropin (ACTH) in your blood 2.5 hours after receiving an injection of glucagon. ACTH is a hormone produced by the pituitary gland that tells your adrenal glands to release cortisol. This test evaluates how well your adrenal glands are working and whether they respond appropriately to stimulation.
How is the test performed, and what steps are involved in the procedure?
The test typically involves the following steps: First, a healthcare provider will draw a baseline blood sample. Then, you will receive an injection of glucagon (usually in the arm muscle). After 2.5 hours, another blood sample will be drawn to measure your ACTH levels. The entire procedure usually takes about 3 hours. You may be asked to fast overnight before the test.
What should I expect during the test, including how long it takes and how it will feel?
During the test, you may experience some discomfort from the needle prick. The glucagon injection might cause temporary side effects such as nausea, flushing, or dizziness. These symptoms are usually mild and subside quickly. It is important to remain relaxed and follow your healthcare provider's instructions throughout the procedure.
Are there any risks or side effects, and do I need to prepare in any special way beforehand?
Before the test, your doctor may ask you to fast overnight and temporarily stop certain medications, especially steroids or hormonal treatments. The risks are minimal and include minor bleeding, bruising, or infection at the injection site. If you have a known allergy to glucagon or have certain medical conditions, inform your doctor beforehand.
Reference range
Reference range varies by laboratory methodology and clinical context. Peak ACTH levels 2.5 hours post-glucagon typically range from 10-30 pmol/L (45-135 pg/mL) in healthy adults. Interpretation should be correlated with clinical presentation and concurrent cortisol measurements.N/A
Patient should avoid corticosteroid medications for 24-48 hours prior to testing as directed by physician. No fasting required. Inform patient about the glucagon stimulation procedure and obtain informed consent. The glucagon stimulation test involves intramuscular or subcutaneous injection of glucagon followed by serial blood draws.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
This test is primarily used to evaluate adrenal gland function and diagnose conditions such as Cushing's disease, adrenal insufficiency, or pituitary disorders. By measuring ACTH levels after glucagon stimulation, doctors can determine if the adrenal glands are producing adequate cortisol in response to hormonal signals. Abnormal results may indicate overproduction or underproduction of cortisol, guiding further diagnostic steps and treatment plans.
Frequently asked questions
Why is glucagon used for this test?
How long does the test take?
Do I need to fast before the test?
Are there any side effects from the glucagon injection?
When will I get my results?
Sources
- 1
- 2
- 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