Homocysteine in coronavirus disease (COVID-19): a systematic literature review

Objectives: Coronavirus disease 2019 (COVID-19) is a life-threatening infectious disorder characterized by a sustained prothrombotic state. Since homocysteine is a potential biomarker of thrombotic diseases, the aim of this article is to provide an updated overview on the possible role played by hyperhomocysteinemia in influencing an unfavorable COVID-19 progression. Methods: We carried out an electronic search in Medline (PubMed interface) using the keywords ("COVID-19" OR "SARS-CoV-2") AND "homocysteine", between 2019 and the present time, with no language restrictions, to identify all articles which explored the concentration of homocysteine in COVID-19 patients with or without unfavorable disease progression. Results: Three studies, totaling 694 hospitalized COVID-19 patients, were included in our systematic review. Overall, the differences between the mean homocysteine values in non-severe vs. severe COVID-19 patients were always positive (i.e., 15.1%, 24.1% and 22.8%, generating a positive weight mean difference of 1.75 mu mol/L (95%CI, 1.26-2.25 mu mol/L; p=0.011), which translates into a cumulative difference of approximately similar to 1.2 mu mol/L. Conclusions: Despite the limited evidence that has been garnered so far, increased homocysteine levels may be a potentially useful marker for predicting the risk of unfavorable progression in patients with COVID-19.