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Cortisol Stimulation Test (Plasma) with ACTH Stimulation

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

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

Quick summary

["Assesses adrenal gland function after a hormone challenge."]

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

Key facts at a glance

LOINC
34542-1
Short code
ACTH Stim IV Pnl SerPl
Synonyms
ACTH Stim IV 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 order this test if they suspect adrenal insufficiency (such as Addison’s disease), Cushing’s syndrome, or other adrenal-related conditions. It helps determine if your adrenal glands are producing cortisol at the expected levels in response to stimulation.

What to Expect Before the Test

You’ll typically have blood drawn twice: once before receiving ACTH and again 1–2 hours later. Follow any fasting or preparation instructions provided by your healthcare team.

How the Test Works

A synthetic ACTH hormone is administered to trigger cortisol production. Blood samples are taken to measure cortisol levels before and after stimulation, helping identify adrenal function.

Possible Results & Interpretation

Results compare baseline cortisol to post-stimulation levels. Low cortisol after ACTH suggests adrenal insufficiency; elevated levels may indicate other conditions like Cushing’s syndrome or medication use.

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 Stim Test (Plasma)

Frequently asked questions

What does a ‘normal’ result mean?
A ‘normal’ result means your adrenal glands responded appropriately to ACTH stimulation, producing cortisol at expected levels. However, your doctor will interpret results in the context of your full medical history and symptoms.
How long does it take to get results?
Results are typically available within 1–3 business days, depending on lab processing times. Your healthcare provider will discuss findings with you during a follow-up visit.
Can I eat or drink before the test?
Follow your doctor’s instructions, but generally, fasting for 8 hours before the first blood draw is common. Avoid caffeine or alcohol before testing, as they may affect cortisol levels.
  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