Variability of fasting and post-methionine plasma homocysteine levels in normo- and hyperhomocysteinaemic individuals.
To assess the variability of plasma homocysteine levels, fasting and post-methionine homocysteine levels were measured twice, at baseline and after follow-up of 1-4 months, in 16 individuals with normal and 26 with elevated homocysteine levels after methionine loading. The intra-individual coefficients of variation varied from 15 to 23% for fasting and post-methionine homocysteine levels, whether these levels were within the normal range or not. As a result, test-retest agreement was poor when subjects were dichotomized as having 'normal' or 'abnormal' homocysteine levels (itself a questionable concept). There was a relation between the average post-methionine homocysteine levels (at the first and second measurement) and the difference between both measurements (r = 0.37, P = 0.016). In normohomocysteinaemic individuals, delta (i.e., the difference between baseline and follow-up) fasting homocysteine and delta post-methionine homocysteine were correlated negatively with delta folate serum levels: r = -0.64, P = 0.007 and r = -0.50, P = 0.05, respectively. Individuals homozygous for the 677 C-->T mutation in the 5,10-methylenetetrahydrofolate reductase gene showed a greater variation of fasting homocysteine levels than those homozygous for the wild type (P = 0.017). In summary, we suggest that there is a substantial intra-individual variability in plasma homocysteine levels over time and that this variability is significantly related to the variability in serum folate levels, especially in normohomocysteinaemic individuals.
van den Berg
M
M
Institute for Cardiovascular Research, Vrije Universiteit, Amsterdam, The Netherlands.
de Jong
S C
SC
Devillé
W
W
Rauwerda
J A
JA
Jakobs
C
C
Pals
G
G
Boers
G H
GH
Stehouwer
C D
CD
D045103:5,10-Methylenetetrahydrofolate Reductase (FADH2); D000328:Adult; D000704:Analysis of Variance; D005215:Fasting / Q000502:physiology*; D005260:Female; D005492:Folic Acid / Q000097:blood / Q000502:physiology; D006710:Homocysteine / Q000097:blood* / Q000502:physiology; D006720:Homozygote; D006801:Humans; D020138:Hyperhomocysteinemia / Q000175:diagnosis* / Q000503:physiopathology*; D008297:Male; D008715:Methionine / Q000378:metabolism; D042965:Methylenetetrahydrofolate Reductase (NADPH2); D008875:Middle Aged; D009154:Mutation; D010088:Oxidoreductases / Q000235:genetics; D018709:Statistics, Nonparametric
D006710:Homocysteine; D005492:Folic Acid; D008715:Methionine; D010088:Oxidoreductases; D045103:5,10-Methylenetetrahydrofolate Reductase (FADH2); D042965:Methylenetetrahydrofolate Reductase (NADPH2)