Skip to content

Cortisol, Serum (Afternoon)

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

This test measures cortisol levels in your blood taken after midday to assess your body’s cortisol production, often used to evaluate adrenal function or adrenal insufficiency.

Quick summary

["This test helps diagnose conditions like Cushing’s syndrome or adrenal gland issues by checking cortisol levels at a specific time of day."]

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

Key facts at a glance

LOINC
66733-7
Short code
Cortis afternoon SerPl-msCnc
Synonyms
Cortis afternoon SerPl-msCnc
Category
hormone
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
0
Ref high
17
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 Is This Test Done?

Your healthcare provider may order this test if you have symptoms like unexplained weight gain, fatigue, or high blood pressure, or if they suspect conditions affecting your adrenal glands. It may also be used to confirm or rule out Cushing’s syndrome or adrenal insufficiency.

What to Expect Before the Test

No special preparation is needed, but you should avoid caffeine or stress-inducing activities for a few hours before the blood draw. Bring any medications you’re currently taking to discuss with your provider.

What Happens During the Test?

A healthcare professional will draw blood from a vein in your arm. The process is quick and typically painless. You may feel slight discomfort, but it usually lasts only a few minutes.

What Are the Results Used For?

Results help determine whether your cortisol levels are too high or too low, guiding treatment decisions for conditions like hormonal imbalances or adrenal disorders.

Reference range

NCBI: NSE 0-17 ng/mLN/A

Specimen: serum

No special preparation usually required. Stay well hydrated. Inform your healthcare provider of all medications and supplements you are taking.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Afternoon Serum Cortisol

Frequently asked questions

Why is my test called 'afternoon serum cortisol'?
This timing helps distinguish between normal circadian (daily) variations in cortisol levels and potential adrenal disorders. Cortisol naturally peaks in the morning and declines later in the day.
What if my results are outside the normal range?
Your provider will discuss the results with you and may recommend further testing or adjustments to your treatment plan, depending on your symptoms and medical history.
Can I eat or drink before the test?
You can have a light snack or drink water, but avoid caffeine or alcohol for at least 2 hours before your blood draw.
  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