Total testosterone measures both protein-bound and unbound testosterone in your blood. Free testosterone refers to the unbound portion. They describe different measurements, so a number from one cannot be compared directly with a number from the other.
If you have searched for an ideal testosterone level, you have probably seen those measurements mixed together. Before debating whether your number is good, establish what was measured.
The name of the test changes the question
MedlinePlus explains the distinction: most circulating testosterone is attached to proteins, including sex hormone-binding globulin, or SHBG, and albumin. Total, free and bioavailable testosterone tests measure different portions.
That does not make the most complicated report the best report. Nor does it make free testosterone a shortcut to a diagnosis. The useful question is why your physician chose that measurement and how it helps explain the problem being investigated.
Read the report before reading the commentary beneath somebody else's screenshot.
The terms on a testosterone report
| Term | What it describes | Question to ask |
|---|---|---|
| Total testosterone | Bound and free testosterone together | What does this result mean in my clinical context? |
| Free testosterone | The unbound portion | Was it measured or calculated, and by which method? |
| SHBG | A protein that binds sex hormones | Does this help explain the other results? |
| Bioavailable testosterone | Free testosterone plus the portion bound to proteins other than SHBG | Why was this measurement selected? |
The definitions come from the MedlinePlus testosterone test guide. The questions are a way to have a clearer conversation, not a request for everyone to order every test.
Check these details before comparing results
1. Copy the test name exactly.
Do not shorten everything to testosterone. If the report says calculated free testosterone, keep the word calculated. Precision here prevents a surprisingly basic comparison error.
2. Keep the units attached.
A number without its unit is incomplete. Do not compare a result reported in one unit with a chart using another unless the conversion has been checked. You should not need to reconstruct the report from memory during an appointment.
3. Preserve the laboratory's reference interval.
Keep the range printed beside that specific result. If you tested at different laboratories, show both reports. Ask whether the methods and intervals are comparable before declaring a trend.
4. Include collection details and the reason for testing.
Record when the sample was taken and what symptoms prompted it. A monitoring test while taking prescribed treatment is a different situation from an initial investigation. Make that distinction explicit.
Comparing reports across countries
A US result and a UK or Australian result may use different concentration units or reference intervals. Check whether the report says ng/dL, nmol/L or another unit, and whether it describes total or free testosterone. Do not copy a threshold from another country's website into a report with different units. Ask the laboratory or ordering clinician to check any conversion and explain the interval used.
What SHBG can add to the discussion
The MedlinePlus SHBG guide explains how this binding protein can help clinicians understand hormone availability when a total result does not explain the clinical picture.
That is a reason to ask about interpretation. It is not a reason to treat SHBG itself as a score you must force upwards or downwards.
Ask: does this finding change the interpretation, and would another measurement change the decision? A useful answer should connect the lab work to your symptoms and medical history.
If you are still deciding whether to test, start with low testosterone symptoms in men. If a supplement advert started the search, read how to assess testosterone booster claims.
Frequently asked questions
What is the difference between free and total testosterone?
Total measures bound and unbound testosterone together. Free refers to the portion not attached to proteins.
Is free testosterone always the better test?
The useful test depends on the clinical question. Ask why it would add information rather than assuming more measurements are always better.
What does SHBG stand for?
SHBG means sex hormone-binding globulin. It is a protein involved in binding circulating sex hormones.
Can I compare my free testosterone with someone else's total testosterone?
No. They measure different portions, and the units and laboratory methods also matter.
What should I bring to a hormone results appointment?
Bring the complete reports, collection details, medication list and a description of the symptoms or question that led to testing.
The short version
Test name, units, method and context come before interpretation. Get those details right before trying to turn a lab result into a health verdict.
This article is general education, not medical advice. It does not replace your own physician.
