The clinical application value of homocysteine

Homocysteine (Hcy) is produced in the process of essential amino acid methionine to cysteine conversion, and participates in DNA metabolism through methylation. In recent years, many studies have shown that serum Hcy levels were directly or indirectly related to various diseases, such as arteriosclerosis, cardiovascular disease, hypertension, neurological disease, diabetes, cancer, pregnancy disease, eye disease and osteoporosis. The normal range of Hcy in human plasma is 5-15 μmol/L, and >15 μmol/L is hyper homocysteine (HHcy). Gene mutations, malnutrition caused by folic acid, vitamin B₆, and B₁₂ deficiency, and a high-methionine diet are common causes of elevated Hcy. Studies have confirmed that the methylenetetrahydrofolate reductase (MTHFR) C677T gene polymorphism is associated with the susceptibility to elevated plasma Hcy levels, and the expression of the MTHFR 677TT genotype in the Chinese population is significantly higher than that of other races. The pathogenic mechanism of increased serum Hcy levels may be: promotion of inflammation and vascular calcification, impaired lipid peroxidation and antioxidant processes, stimulation of the production of reactive oxygen species, induction of oxidative stress and vascular dysfunction, endothelial cell toxicity and dysfunction, inhibit the release of neurotransmitters, and so on. Other pathogenic mechanisms still need to be further studied. The level of Hcy is important for the risk prediction of the disease, the controlling of the disease complications and the prognosis of the disease. The overall prevalence of HHcy in Chinese population is high, and the regional differences are significant. With the increase of age, the prevalence also increases. Monitoring of Hcy is conducive to early detection and diagnosis of diseases and prevention of serious complications. To provide reference for the clinical application of Hcy, this study comprehensively explores the relationship between Hcy and disease and its pathogenic mechanism on the basis of the latest literatures.