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Cortisol level after ACTH stimulation test (serum/plasma)

Published: August 9, 2026Updated: August 17, 2026

This test measures your cortisol levels before and after a dose of synthetic ACTH (adrenocorticotropic hormone) to check how well your adrenal glands respond to stimulation.

Quick summary

["Assesses adrenal gland function and helps diagnose conditions like adrenal insufficiency."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
34541-3
Short code
ACTH Stim IM Pnl SerPl
Synonyms
ACTH Stim IM Pnl SerPl
Category
hormone
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
10
Ref high
60
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why This Test Is Done

Your doctor may recommend this test if you have symptoms of low cortisol, such as fatigue, dizziness, low blood pressure, or weight loss, or if they suspect an issue with your adrenal glands. It can also help diagnose conditions like Cushing’s syndrome or adrenal insufficiency.

How the Test Works

You’ll receive an injection of synthetic ACTH, which stimulates your adrenal glands to produce cortisol. Blood samples are taken before and after the injection to measure your cortisol levels.

What to Expect During the Test

The procedure is quick and usually done in a doctor’s office or lab. You may feel some mild discomfort from the injection, but no other side effects are expected. You’ll need to stay for a short time to have blood drawn at different intervals.

Preparation Before the Test

No special preparation is needed, but inform your doctor about any medications you’re taking, especially steroids or blood pressure medications. Avoid caffeine or large meals before the test if instructed.

Reference range

NCBI: ACTH 10-60 pg/mLN/A

Specimen: serum

Typically collected in the morning (8-10 AM). Inform your provider if taking steroid medications.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

ACTH Stimulation Test

Frequently asked questions

What does a low cortisol level mean?
A low cortisol level after the ACTH injection suggests your adrenal glands are not functioning properly to produce cortisol when needed. This could be due to adrenal gland damage, autoimmune disease, or other conditions causing adrenal insufficiency.
What does a high cortisol level mean?
Elevated cortisol levels after stimulation may indicate overproduction of cortisol by the adrenal glands, which can be caused by conditions like Cushing’s syndrome, tumors, or prolonged use of steroid medications.
How long does it take to get results?
Results are typically available within a few days to a week, depending on your lab. Your doctor will discuss the findings with you during a follow-up visit.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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.

Medical Disclaimer

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 17, 2026. · Read our editorial policy