Testosterone lab test names on orders and results, decoded

Testosterone tests go by several names, and they change from lab to lab. A name on an order or a result can tell you whether you are getting total or free testosterone, and sometimes how it was measured. This page decodes the common ones.

Free and total testosterone

Free and total testosterone on one order, so you get both numbers from one draw.

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Names for the hormone itself

Name you may see	What it means
Testosterone, total; Total testosterone; Serum testosterone	All testosterone in the blood, bound to proteins and unbound. MedlinePlus lists “serum testosterone” and “total testosterone” as other names for the test, and calls it the most common type.
Testosterone, free; Free testosterone	Only the unbound portion. Less common than total, per MedlinePlus.
Testosterone, free, direct; Free direct	A free testosterone value from a direct immunoassay, not a calculation. See below.
Testosterone, total and free; Free and total testosterone	Both measurements on one order.
Testosterone, bioavailable; Testosterone, total and bioavailable	Free testosterone plus testosterone attached to proteins other than SHBG, per MedlinePlus. Not commonly done.
Free testosterone, calculated	An estimate worked out from total testosterone, SHBG and albumin with a formula.

A trailing “S” or the word “serum” often marks the specimen type. In one reference laboratory’s catalog, for example, the reporting name is “Testosterone, Total, S” and the specimen is serum.

What “direct” means in a free testosterone name

“Direct” in a free testosterone name usually points to a direct immunoassay run on the sample, not a value worked out from other results. One large lab’s test with this name lists a direct analog enzyme immunoassay. “Calculated” says the opposite: the lab estimated it from total testosterone, SHBG and albumin with a formula. The Endocrine Society guideline accepts calculating free testosterone by formula when equilibrium dialysis is not available.

A name is a label, not a ranking. If your report prints a method, the method labels below explain the common ones. Free vs total testosterone explains why free testosterone is measured at all.

If you want both numbers from one order, look for “free and total testosterone”. If you already have total and SHBG results, the free testosterone calculator estimates free testosterone from them.

• Free and total testosteroneBoth numbers on one order $99 See this test at HealthLabs
• Free testosteroneFree testosterone only $59 See this test at HealthLabs
• Total testosteroneTotal testosterone only $49 See this test at HealthLabs

Sold by HealthLabs. Prices checked October 2026. Not available in ND, RI, NY, NJ, MD and HI. We earn a commission on sales.

Method labels

Some orders and reports add a method. The guideline says total testosterone is measured by radioimmunoassay, immunometric assays or liquid chromatography-tandem mass spectrometry (LC-MS/MS). It says LC-MS/MS generally offers higher specificity, sensitivity and precision, especially at low levels, than most immunoassays. It also says there is large variation between laboratories, and it recommends an assay certified by an accuracy-based program such as the CDC Hormone Standardization Program.

Label	What it means
LC-MS/MS; mass spectrometry	Liquid chromatography-tandem mass spectrometry, a lab method
Immunoassay; RIA	A family of methods that includes radioimmunoassay and immunometric assays
Equilibrium dialysis; dialysis	A method for measuring free testosterone, per the guideline
Calculated; calc	A value worked out from other results

A method label doesn’t tell you the result is right or wrong for you. It tells you how the number was made, which helps when comparing results from different labs.

Units

Results are reported in different units, and the same number means different things in each.

• Total testosterone is commonly shown in ng/dL or nmol/L. The guideline, for example, gives 264 ng/dL as 9.2 nmol/L.
• Free testosterone may be in ng/dL or pg/mL, depending on the lab. One reference laboratory’s catalog reports it in ng/dL. The guideline quotes a free testosterone value of 64 pg/mL (220 pmol/L).

Always compare a result with the range printed beside it, in the same unit. Don’t compare a ng/dL figure with a nmol/L range.

Other orders that appear beside testosterone

These are separate markers, not alternative names:

• SHBG is the main binding protein. See SHBG.
• LH and FSH are pituitary hormones. See LH and FSH in men.
• Estradiol is an estrogen. See estradiol in men.
• Prolactin is another pituitary hormone. See prolactin for men.

Reading a result line

A typical line shows the test name, your result, the unit and the lab’s reference range, often with a flag if the result is outside it. The range differs between labs and assays, so use the one on your own report. For published ranges with sources, see testosterone levels by age.

A result alone can’t diagnose anything. MedlinePlus says to talk to your provider if you have questions about your results.