FPSA, which means free prostate specific antigen in Chinese, is a sensitive indicator for the diagnosis of prostate cancer, but it has to be combined with total prostate cancer specific antigen to make a specific distinction. When the total prostate specific antigen is found to be between 4 and 10 ng/ml during the clinical blood test for prostate cancer, this is the gray level of the diagnosis and the ratio of free prostate specific antigen to total prostate specific antigen is needed. If the ratio is less than 0.25 or even less than 0.15, the patient should be alert for prostate cancer. Patients are advised to have an anal exam, or a transprostatic ultrasound, and an MRI of the prostate, or MRI spectroscopy. If abnormal nodules and abnormal signals are found, the patient should undergo a puncture biopsy of the prostate to determine if there is a prostate cancer lesion. Elevated prostate free antigen is also associated with recent masturbation, sexual intercourse, smoking, alcohol consumption, trauma, and urinary tract infections, which cause inflammatory problems in the urinary tract, so patients who find abnormal values should make specific distinctions.