It follows therefore that PSA is an organ-specific rather than a cancer-specific serum marker, which means that the elevation of PSA levels in patients with negative biopsies can be caused by benign prostatic hyperplasia (BPH) and prostatitis.[2] Compensating for the limitations of PSA tests is achieved by adjusting PSA levels according to prostate volume (PV), known as PSA density (PSAD).[7, 8]. The gene discussed is KLK3; the disease is benign prostatic hyperplasia.