Vitalicore • Hormone Balance • UK
Free vs total testosterone: SHBG, calculated results and what to ask
The names on a testosterone report describe different measurements. This guide helps you read the report accurately and prepare questions without diagnosing yourself.
Quick answer: total and free measure different things
Total testosterone includes the testosterone attached to blood proteins and the small unbound fraction. Free testosterone refers to that unbound fraction. SHBG and albumin are binding proteins. A free result is not automatically a better first test or a diagnosis.
Read the report before comparing numbers
| Report item | What to look for | Question to ask |
|---|---|---|
| Total testosterone | The result, units and laboratory interval | Was the sample suitable for interpretation? |
| SHBG | Whether it was measured and whether it is within range | Would it change interpretation of my total result? |
| Calculated free testosterone | The calculation method and inputs, which may include total testosterone, SHBG and albumin | Is the calculation appropriate for this laboratory and my situation? |
| Direct free testosterone | Which laboratory method was used | Was this an appropriate method, rather than an unspecified “free T” claim? |
When SHBG and calculated free testosterone can help
The UK joint position statement recommends checking SHBG in borderline total testosterone results or where a condition may alter SHBG. When SHBG is normal, calculated free testosterone adds no diagnostic value beyond total testosterone. With high or low SHBG it may help a clinician resolve a misleading total value. It does not explain every symptom.
Do not compare unlike numbers
Keep the result beside its own units, method and laboratory range. A total testosterone result and a free testosterone result should not be read against the same range. Screenshots that omit units or collection details can make a comparison misleading.
- Keep the original PDF or report, rather than copying a number from memory.
- Ask the laboratory whether “free” means calculated or directly measured; do not guess from the price or brand.
- Record the collection time, preparation and whether you were ill.
- If two laboratories disagree, ask which method and interval each used before drawing a conclusion.
Is a calculated result more accurate than a direct test?
It depends on the direct method. Equilibrium dialysis followed by mass spectrometry is the reference method for free testosterone in the joint guidance. Other direct methods may be unreliable. A calculation is also dependent on its inputs and assumptions, so “calculated” is not a universal accuracy guarantee.
See test accuracy and laboratory methods for the distinction between collecting a sample and analysing it.
Questions for clinical follow-up
- Does my total result fit my symptoms and the sampling conditions?
- Would SHBG add useful information in my case?
- If free testosterone is shown, how was it obtained?
- Is a repeat sample needed before deciding the next step?
Use the GP appointment notes to keep the questions and report details together.
Choose the next question
Sources and review boundary
- UK joint position statement: total testosterone, SHBG and free testosterone
- Lab Tests Online UK: SHBG
- Royal United Hospitals Bath: calculated free testosterone
Updated against the linked sources on 18 October 2026 by the Vitalicore editorial team. Educational decision support; no individual diagnosis or independent clinical review is claimed.
Frequently asked questions
Is free testosterone always the better test?
No. Total testosterone is a common starting measurement. Additional markers and calculations are useful in selected clinical situations.
Can a normal total testosterone result explain persistent symptoms?
A result does not explain all symptoms. A clinician can consider the sampling conditions, SHBG where relevant and other possible causes.
Should I use the same reference range for total and free testosterone?
No. Use the units and laboratory range printed beside each result and ask for clarification if they are missing.