Other situations to avoid testosterone replacement therapy include men seeking fertility, the presence of a hormone-related cancer (breast or prostate cancer), or suspicion of prostate cancer and/or lower urinary tract symptoms, high levels of prostate specific antigen (PSA) (> 4 ng/mL or > 3 ng/mL in men with increased risk), uncontrolled obstructive sleep apnoea or heart failure, or recent (within the last 6 months) myocardial infarction or stroke, elevated haematocrit or thrombophilia [10]. Here, KLK3 is linked to heart failure.