Sample preparation in patients receiving uric acid oxidase (rasburicase) therapy.

etary riboflavin, neither were they related to EGRAC or plasma ribofla-vin. This supports the use of EGRAC, and, to a lesser extent, plasma ribo-flavin, as a marker of riboflavin status that reflects dietary intake. We do not agree with the suggestion that the improvement in folate status in the folate-rich diet should have compromised riboflavin status, as it did in the folic acid supplemen-tation period, because riboflavin intake after this intervention increased significantly from 1.45 Ϯ 0.51 mg/ day at baseline to 1.85 Ϯ 0.61 mg/ day (P Ͻ0.001). This is to be expected because the folate-rich cereals consumed are also good sources of ribo-flavin. We do, however, accept that a decrease in riboflavin intake might have contributed to the observed effect of folate supplementation on measures of riboflavin status. The study design incorporated 4-month intervention periods without any washout period. Subjects were considered to have reached a " steady state " by the end of each intervention, and comparison was made between measurements at the end of each intervention; a comparison with baseline was also made before any intervention. Justification for this design was established on the basis of known characteristics of erythrocyte turnover, which is ϳ120 days. Concerns in this regard are fewer for riboflavin, which, unlike folates, readily enters circulating erythrocytes from the plasma. For this reason, and as has been known for many years, EGRAC is sensitive in the short term to dietary intake of riboflavin (4). We do not accept the suggestion that we have underestimated the prevalence of riboflavin deficiency. The most common measure of riboflavin status in current use is EGRAC. It is accepted that there is a discrepancy between estimates of ri-boflavin deficiency through the use of EGRAC and estimates made from dietary intakes, such as to suggest either an overestimate of bioavail-ability or an inappropriately low EGRAC threshold for normality. After using an established analytical method over many years, it is our experience, and that of others, that a cutoff value Ͼ1.4 more adequately reflects the distribution of values in a human population and has more functional relevance than a lower cutoff value (5–7). Effect of riboflavin status on the homocysteine-lowering effect of folate in relation to the MTHFR (C677T) genotype. et al. Methyl-enetetrahydrofolate reductase (C677T) genotype modulates blood folate and homocysteine responses to a folate rich diet or a low dose folic acid supplementation: a randomized controlled trial. Am J …