Plasma creatinine as a determinant of plasma total homocysteine concentrations in the Hordaland Homocysteine Study: use of statistical modeling to determine reference limits.
OBJECTIVE
We established population-based reference limits for plasma total homocysteine (tHcy) according to creatinine.


METHODS
In 7042 middle-aged and elderly subjects from the Hordaland Homocysteine Study, we used statistical modeling to establish nomograms for tHcy according to creatinine in the whole population and in folate-replete and healthy subgroups.


RESULTS
When plotted against creatinine, tHcy 97.5th percentile almost overlapped in men and women, and, in elderly, increased up to 8 micromol/L from the 2.5th to 97.5th creatinine percentiles. Folate-replete subjects had tHcy upper limits approximately 20% below the whole population at all creatinine levels. Healthy subjects had lower creatinine, but at a given creatinine level, tHcy was the same as in the whole population.


CONCLUSIONS
tHcy difference between men and women is mostly explained by creatinine. The tHcy-reducing effect of folate is independent of creatinine. In elderly people, creatinine should be taken into account when assessing tHcy levels.
Elshorbagy
Amany K
AK
Oxford Centre for Gene Function, Department of Physiology, Anatomy and Genetics, Oxford University, UK. amany.elshorbagy@dpag.ox.ac.uk
Oulhaj
Abderrahim
A
Konstantinova
Svetlana
S
Nurk
Eha
E
Ueland
Per M
PM
Tell
Grethe S
GS
Nygård
Ottar
O
Vollset
Stein E
SE
Refsum
Helga
H
D000328:Adult; D000367:Age Factors; D000368:Aged; D003404:Creatinine / Q000097:blood* / Q000378:metabolism; D005260:Female; D005492:Folic Acid / Q000097:blood; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D007677:Kidney Function Tests; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D012737:Sex Factors; D014805:Vitamin B 12 / Q000097:blood
D006710:Homocysteine; D005492:Folic Acid; D003404:Creatinine; D014805:Vitamin B 12