For borderline levels between 2.31 and 3.46 ng/ml and in conditions with altered sex hormone-binding globulin (SHBG) levels (e.g., ageing, hyperthyroidism, liver disease, HIV infection), calculated free testosterone (cFT) determination could be helpful to reach a diagnosis [3], although standard cutoff isn’t well defined. The gene discussed is SHBG; the disease is HIV infectious disease.