Testosterone
Testosterone is the main male sex hormone; women have it too, in smaller amounts. It is highest in the morning.
At a glance
- Sample
- Blood
- Units
- ng/dL (US), nmol/L (Europe)
- Often looked at with
- Estradiol, Cortisol, Prolactin
- Preparation
- The level is highest in the morning, so blood is usually drawn in the morning. Sometimes you are asked to come fasting.
Units: ng/dL and nmol/L
US labs usually print testosterone in ng/dL, most European labs in nmol/L. To convert, divide ng/dL by 28.842.
nmol/L = ng/dL ÷ 28.842 · molar mass 288.42 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 testosterone result against the range printed by the lab that measured it.
What can affect the result
- Time of day: highest in the morning, so it is taken before 10:00.
- A recent illness or lack of sleep.
- Biotin supplements can skew some methods.
If something like this applies, mention it to the doctor who reads your results.
Questions
How do I convert testosterone from ng/dL to nmol/L?
Divide ng/dL by 28.842. For example, 500 ng/dL is 17.3 nmol/L.
Why does my lab’s testosterone 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 testosterone test?
The level is highest in the morning, so blood is usually drawn in the morning. Sometimes you are asked to come fasting. Follow your lab’s instructions.
Related tests
Got a lab report with Testosterone?
Share it to Soma: it reads every row on your phone, with no account and no upload, and puts your testosterone on one chart with your earlier results, each against the range your lab printed.
Sources
- Testosterone Levels Test — MedlinePlus, U.S. National Library of Medicine.
- Units: PubChem: Testosterone (testosterone), molar mass 288.42 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.