Cystatin C is an Independent Predictor of Fasting and Post-Methionine Load Total Homocysteine Concentrations Among Stable Renal Transplant Recipients (Endocrinology and Metabolism‪)‬

In recent years, hyperhomocysteinemia has been shown to be an independent risk factor for occlusive vascular diseases (1-5). An increased prevalence of hyperhomocysteinemia has been observed in renal transplant recipients (RTRs)[5] (6-12), and it has been reported that hyperhomocysteinemia may contribute to the disproportionately high incidence of cardiovascular disease events experienced by RTRs (7,12-15). In a recent prospective study of 207 chronic, stable RTRs, Ducloux et al. (16) demonstrated that increased fasting total homocysteine (tHcy) is an independent risk factor for the development of cardiovascular disease events in stable RTRs. Hyperhomocysteinemia is characterized by mild to moderately increased concentrations of plasma tHcy, as measured during fasting or 2-6 h after a methionine load. Boushey et al. (3) showed, in a metaanalysis of 27 studies, that both fasting and post-methionine load (PML) hyperhomocysteinemia are risk factors for coronary artery disease. Additionally, results from our laboratory (17), as well as from the European Concerted Action Project (5) and the National Heart, Lung, and Blood Institute Family Heart Study (4), showed that PML and fasting hyperhomocysteinemia are independent of each other in the majority of individuals and that without methionine loading, ~27-40% of the cases of increased plasma tHcy could be missed. Despite the importance of measuring tHcy concentrations after a methionine load, only one study, involving 29 RTRs, has documented that there is an increased prevalence of both fasting and PML hyperhomocysteinemia in RTRs (9).