Relevance of plasma levels of free homocysteine and methionine as risk predictors for ischemic stroke in the young.

BACKGROUND & AIMS: The debated vascular risk potential of total homocysteine (tHcy), due to failed clinical trials designed on B vitamin supplementation, raises many possible explanations like the higher risk potential of the deleterious, free form of homocysteine (fHcy) or, the unchecked confounding effects of B-vitamins in tHcy-based association studies. Additionally, the cardiovascular risk probability of altered status of the homocysteine precursor, methionine (tMet) could shed light on the causality of association between tHcy and cardiovascular diseases. Hence, we aimed to evaluate the risk associations of elevated plasma levels of tHcy, fHcy and low levels of tMet with premature, ischemic stroke. METHODS: We recruited 171 young, ischemic stroke patients (aged ≤45 years) and 249 age- and gender-matched healthy controls. Plasma levels of fHcy, tHcy, tMet and vitamin B6 were estimated using HPLC coupled with coulometric electrochemical detection. Plasma levels of vitamin B12 and folate were estimated by radioimmunoassay. RESULTS: Elevated fHcy (>2.9 µmol/L) was independently and strongly associated with the risk of premature, ischemic stroke (OR = 9.62, 95% CI = 3.51-26.40). On the contrary, association between premature ischemic stroke and elevated tHcy (>15.0 µmol/L) was found to attenuate when adjusted for vitamin B6 values (OR = 0.24, 95%, CI = 0.03-1.69). Interestingly, compromised B6-status (<59.2 nmol/l) was found to confer high risk of premature ischemic stroke (OR = 170.80, 95% CI = 58.22-501.06). We could not establish any significant correlation between fHcy and B-vitamin levels (P > 0.05). Low tMet (<13.86 µmol/L) was also not significantly associated with premature, ischemic stroke (OR = 2.53, 95% CI = 0.613-10.38). CONCLUSION: Our results indicate significant but not-correlated, independent associations of fHcy and vitamin B6 with risk of premature, ischemic stroke. However, the causality of these associations need prospective and large scale validations. Further, our findings highlight the crucial confounding effects of B-vitamins on risk association between tHcy and premature ischemic stroke.

Plasma S-adenosylhomocysteine: A potential risk marker for cerebral venous thrombosis.

BACKGROUND: Despite a plethora of studies suggesting that hyperhomocysteinemia is associated with an increased risk for arterial and venous thrombosis, there is paucity of data on the role of the S-adenosylhomocysteine (SAH), the metabolic precursor of homocysteine (Hcy) as a risk predictor for cerebral venous thrombosis (CVT). METHOD: We estimated fasting plasma concentrations of total homocysteine (tHcy), SAH and S-adenosylmethionine (SAM), in 185 CVT patients and 248 healthy controls, by reverse-phase high performance liquid chromatography coupled with coulometric electrochemical detection. RESULTS: Fasting tHcy, SAH and SAM were significantly higher in patients compared with controls. Increased tHcy and SAH concentrations were associated with 4.54-fold (95% CI, 2.74-7.53) and 35.77-fold (95% CI, 19.45-65.79) increase in risk for CVT, respectively. Receiver operating characteristic (ROC) curve analysis showed that the area under curve, sensitivity and specificity was higher for SAH compared to tHcy. Further, discriminant analysis to distinguish between tHcy and SAH showed that SAH had a significantly higher percentage classification, with lower Wilk's lambda and higher χ(2), compared to tHcy. CONCLUSION: Increased plasma SAH may be a more sensitive risk marker for CVT than plasma tHcy.