Cortisol
The body's main stress hormone, produced by the adrenal glands in a daily rhythm.
| Typical reference range | 4–22 ug/dL |
Ranges vary by laboratory, method, age and sex: always use the range printed on your own report. Why labs differ.
What it measures
Cortisol is a glucocorticoid released by the adrenal glands under control of ACTH from the pituitary. It peaks within an hour of waking and falls to its lowest around midnight, regulating blood sugar, blood pressure, immune response and metabolism.
Why it matters
Morning cortisol screens for adrenal insufficiency (very low values) and, with other tests, for Cushing's syndrome. Chronically elevated cortisol contributes to insulin resistance, abdominal fat, muscle loss, bone loss and high blood pressure.
What a high result can mean
High levels occur with acute physical or psychological stress, illness, poor sleep, oral contraceptives or estrogen (which raise binding globulin), pregnancy, corticosteroid medications (some cross-react), heavy alcohol use, depression and Cushing's syndrome.
What a low result can mean
Low morning cortisol can indicate adrenal insufficiency (Addison's disease) or pituitary insufficiency, or suppression from current or recent glucocorticoid use, including inhaled, topical or injected steroids.
What affects the result
Must be drawn in the morning (about 7-9 am) to compare with the reference range; afternoon values are naturally much lower. Shift work and poor sleep alter the rhythm. A single serum value cannot diagnose Cushing's; late-night salivary cortisol, 24-hour urine or dexamethasone suppression tests are used.
Units and conversion
Usually reported in ug/dL.
- From nmol/L: multiply by 0.036 to get ug/dL
- From ng/mL: multiply by 0.1 to get ug/dL
Also called on lab reports
Cortisol, AM, Cortisol, Total, Cortisol, Serum, AM Cortisol, Cortisol - AM, Cortisol, Morning, Cortisol, A.M.
Related tests: Adrenal & Pituitary
This page is educational and does not replace advice from a healthcare professional.