Cortisol
Cortisol is a hormone made by the adrenal glands. It helps the body respond to stress; its level is highest in the morning and falls through the day.
At a glance
- Sample
- Blood
- Units
- µg/dL (US), nmol/L (Europe)
- Often looked at with
- Testosterone, Estradiol, Prolactin
- Preparation
- Cortisol changes through the day, so the time of the draw matters: the test is often done in the morning, and sometimes again later in the day.
Units: µg/dL and nmol/L
US labs usually print cortisol in µg/dL, most European labs in nmol/L. To convert, multiply µg/dL by 27.589.
nmol/L = µg/dL × 27.589 · molar mass 362.46 g/mol
This converter changes units only. It doesn’t tell you whether a number is in or out of any range: that depends on the range printed by your own lab, and on your doctor. Soma does not diagnose and is not medical advice.
Why lab ranges differ
Each lab sets its reference range for its own method and analyser, and many ranges differ by age and sex. Two labs can print different ranges for the same blood, so a result is read against the range on its own report, not against a number from another lab or a website.
Soma charts every cortisol result against the range printed by the lab that measured it.
Questions
How do I convert cortisol from µg/dL to nmol/L?
Multiply µg/dL by 27.589. For example, 15 µg/dL is 413.8 nmol/L.
Why does my lab’s cortisol range differ from another lab’s?
Each lab sets its range for its own method and equipment, and many ranges differ by age and sex. That’s why a result is best read against the range printed on the same report.
How do I prepare for a cortisol test?
Cortisol changes through the day, so the time of the draw matters: the test is often done in the morning, and sometimes again later in the day. Follow your lab’s instructions.
Related tests
Got a lab report with Cortisol?
Share it to Soma: it reads every row on your phone, with no account and no upload, and puts your cortisol on one chart with your earlier results, each against the range your lab printed.
Sources
- Cortisol Test — MedlinePlus, U.S. National Library of Medicine.
- Units: PubChem: Hydrocortisone (hydrocortisone, which is cortisol), molar mass 362.46 g/mol, as the Soma app converts.
Mention of a source doesn’t mean it endorses Soma. This page explains the test; it doesn’t diagnose and is not medical advice. Talk to your doctor about what your results mean.