| Marker | Gabriel optimal | Typical lab range | Functional range |
|---|---|---|---|
| Cortisol, AM | 10 to 15 ug/dL | 6.2 to 19.4 | 10 to 15 |
What cortisol does and why timing matters
Cortisol is a hormone made by your adrenal glands. It helps control blood sugar, blood pressure and your response to stress. Levels peak in the morning and fall through the day, so a morning number and an afternoon number mean different things.
That is why a blood test is usually drawn early in the morning, sometimes with a second draw around 4 p.m. Gabriel's morning cortisol lab guide covers the marker in more depth.
Blood, saliva and urine tests
| Test | How it works | Best for |
|---|---|---|
| Blood | A morning draw, sometimes with a second afternoon draw | A snapshot at one time of day |
| Saliva | Samples collected at home at set times | Seeing how cortisol rises and falls across the day |
| 24-hour urine | All urine collected over a day | Total cortisol output over 24 hours |
For a saliva test, avoid eating, drinking, brushing or flossing for 30 minutes before each sample. See cortisol saliva testing and the 4-point salivary cortisol guide.
What high or low cortisol can mean
Higher than expected can point to:
- Stress, acute illness, intense exercise or poor sleep before the test.
- Estrogen, birth control pills or pregnancy, which can change cortisol results.
- Depression, anxiety, heavy alcohol use, poorly controlled diabetes or obesity, which can raise it for a time.
- Cushing syndrome, from long-term high-dose steroid medicines or, less often, a pituitary, adrenal or other tumor.
Lower than expected can point to:
- Steroid medicines (pills, inhalers, creams, eye drops or joint injections), which suppress your own cortisol. This is the most common cause of a low result.
- Addison disease, where the adrenal glands don't make enough cortisol.
- Pituitary problems, where the pituitary doesn't signal the adrenals enough.
What to do with an abnormal result
- Check the timing. Note when you woke and when you were drawn. A late draw reads lower.
- List every medicine, including steroid creams, inhalers and birth control. Never stop a steroid suddenly; ask your prescriber first.
- Repeat before acting. Abnormal results usually lead to repeat or specialized tests, such as a stimulation or suppression test, ordered by a clinician.
Gabriel's optimal band (10 to 15 mcg/dL in the morning) is narrower than most lab ranges. A very low morning cortisol is a reason for medical evaluation, not a number to optimize at home.
Get emergency care for severe weakness, fainting or dizziness on standing, vomiting, or severe belly pain, especially if you take or recently stopped long-term steroid medicines. Low cortisol can first show up as an emergency called adrenal crisis.
Common questions
What is a normal morning cortisol level?
A typical 8 a.m. range is about 5 to 25 mcg/dL (138 to 690 nmol/L), though labs differ. Gabriel's optimal band is 10 to 15 mcg/dL.
What time should a cortisol blood test be done?
Usually early in the morning, when cortisol peaks. Sometimes a second sample is drawn around 4 p.m.
Is a saliva cortisol test better than blood?
They answer different questions. Blood gives a snapshot at one time; saliva samples at several times show your daily rhythm. Your clinician picks the test that fits.
Can stress raise cortisol on a blood test?
Yes. Stress, exercise, poor sleep and illness can raise it, so rest before the test and tell your clinician about anything unusual.
Do birth control pills affect cortisol tests?
They can. MedlinePlus lists birth control pills and estrogen among the medicines that affect cortisol results, so mention them before your test.
Sources
- Cortisol Test MedlinePlus, U.S. National Library of Medicine
- Cortisol blood test MedlinePlus, U.S. National Library of Medicine
- Adrenal Insufficiency and Addison's Disease: Symptoms and Causes National Institute of Diabetes and Digestive and Kidney Diseases (NIH)
This guide is general information, not medical advice. It does not replace a visit with a licensed clinician. Gabriel membership is not health insurance.