What is the disease caused by high prostate PSA index?

The prostate is very important to men, and for middle-aged and elderly men, the prostate is really annoying. Why do I say that? Mainly because as people age, prostate diseases will also appear, which has a huge impact on the quality of life. If the prostate problem is more serious, it may also affect men's normal sex life. So, what is the disease of high prostate PSA index?

PSA is a single-chain polypeptide containing 237 amino acids. It belongs to the family of tissue-specific serine proteases with chymotrypsin-like effects. It can decompose the main collagen in semen and has the effect of diluting semen. PSA can be synthesized in both normal and cancerous epithelial cells. The first secreted into the prostate glandular duct is an inactive zymogen (proPSA), which forms active prostate-specific antigen after cleavage of 7 amino acids at the amino terminus. Most of the prostate-specific antigen that enters the blood circulation quickly binds to protease inhibitors, mainly to α-1 antichymotrypsin (ACT) and α-2 macroglobulin (MG). Some of them are inactivated by protease and exist in a free state.

PSA is tissue-specific and only exists in the cytoplasm of human prostate acinar and ductal epithelial cells, and is not expressed in other cells. However, it is not tumor-specific. Prostatitis, benign prostatic hyperplasia, and prostate cancer can all lead to an increase in total PSA levels (free PSA plus composite PSA).

Prostate cancer

Prostate cancer has surpassed skin cancer to become the most common cancer in North American men and ranks second in cancer-related deaths. PSA is elevated in most clinically significant prostate cancers and is the most important early detection indicator. Although PSA is the most commonly used means of detecting prostate cancer, benign prostatic hyperplasia and prostatitis can also result in a positive PSA. One way to solve this problem is to detect free prostate-specific antigen. Studies have shown that in prostate cancer patients, the vast majority of PSA is in a bound state, and their free PSA/total PSA ratio is lower than that of normal people or patients with benign prostatic hyperplasia. Therefore, for men with abnormally elevated total PSA, free PSA is tested, and the specificity of screening and diagnosing prostate cancer can be improved by calculating the ratio of free PSA to total PSA.

The normal value of serum prostate-specific antigen (PSA) is generally <4ng/mL. When prostate cancer occurs, PSA>10ng/mL, which has significant significance in assisting clinical diagnosis.