A testosterone test usually measures both total testosterone and free testosterone levels, which provide different insights into your hormonal health.
Total testosterone measures the entire amount of testosterone circulating in your bloodstream. It includes testosterone bound to proteins (such as sex hormone-binding globulin, or SHBG), as well as the small portion that is unbound.
Free testosterone refers to the testosterone that is not bound to proteins and is biologically active, meaning your body can use it immediately.
Because of this difference, some men may have normal total testosterone test results but still experience symptoms caused by low free testosterone.
Medical providers evaluate both measurements when they test testosterone levels to determine whether you may have high or low testosterone, abnormal testosterone levels, or signs of hormonal imbalance.
A comprehensive low testosterone test helps your clinical team understand:
- Total testosterone levels
- Free testosterone levels
- Protein-bound testosterone (affected by SHBG)
Looking at these markers together allows your clinician to accurately diagnose low testosterone or other hormonal issues and recommend the most appropriate treatment.