Plasma S-adenosylhomocysteine is a more sensitive indicator of cardiovascular disease than plasma homocysteine

Background: Although plasma total homocysteine has been identified as an independent risk factor for vascular disease in a multitude of studies, there is a considerable overlap in values between patients at risk and control subjects. The difference in values can be used to distinguish statistically between the 2 groups, provided each group is large enough; however, discriminating between individual patients at risk and control subjects is difficult. Objective: We investigated whether the precursor of homocysteine, S-adenosylhomocysteine, is a more sensitive indicator of risk. Design: We measured plasma total homocysteine, S-adenosylhomocysteine, S-adenosylmethionine, creatinine, folate, and vitamin B-12 in 30 patients with proven cardiovascular disease and 29 age- and sex-matched control subjects. Results: The homocysteine values (±SD) were 12.8 ± 4.9 (95% CI; 11.0, 14.7) μmol/L for patients and 11.0 ± 3.2 (9.8, 12.2) μmol/L for control subjects. The S-adenosylhomocysteine values were 40.0 ± 20.6 (32.3, 47.7) nmol/L for patients and 27.0 ± 6.7 (24.5, 30.0) nmol/L for control subjects (P = 0.0021). The S-adenosylmethionine values were 121.8 ± 42.9 (105.8, 137.8) nmol/L for patients and 103.9 ± 21.8 (95.6, 112.2) nmol/L for control subjects (P = 0.0493). The creatinine values were 110 ± 27 (97, 120) μmol/L for patients and 97 ± 9 (80, 100) μmol/L for control subjects (P = 0.0025). Values for folate and vitamin B-12 did not differ significantly between groups. Conclusions: Plasma S-adenosylhomocysteine appears to be a much more sensitive indicator of the difference between patients with cardiovascular disease and control subjects than is homocysteine. Both plasma total homocysteine and S-adenosylhomocysteine are significantly correlated with plasma creatinine in patients.