Use a reliable method and base clinical decisions on published action levels2
The reliability of free testosterone assays based on analog displacement assays has been questioned. Equilibrium dialysis is considered the best diagnostic approach for free testosterone, although it can be more costly than other approaches. Measurement of serum SHBG alongside a reliable measurement of total testosterone allows for calculation of free testosterone level.1
Reference ranges quoted by laboratories represent the normal population.
The action levels recommended by the BSSM refer to men with clinical symptoms of TD. Therefore clinical decisions should be based on published action levels, rather than laboratory reference ranges for low testosterone.2