ARS | Publication request: Subclinical vitamin K deficiency in hemodialysis (HD) patients

Submitted to: American Journal of Kidney Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 22, 2006
Publication Date: March 1, 2007
Publisher's URL: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=17336705&query_hl=1&itool=pubmed_docsum
Citation: Pilkey, R.M., Morton, A., Boffa, M.B., Noordhof, C., Day, A.G., Su, Y., Miller, L.M., Koschinsky, M.L., Booth, S.L. 2007. Subclinical vitamin K deficiency in hemodialysis (HD) patients. Journal of the American Society of Nephrology. 49(3):432-9.

Interpretive Summary: Subclinical vitamin K deficiency has been associated with vascular calcification in healthy adults. Non-dietary determinants of vitamin K status include apolipoproteinE (apoE) genotype, which is believed to influence the transport of vitamin K to various tissues. Vitamin K status in hemodialysis (HD) patients, a clinical population with high rates of vascular calcification, has not been well studied. Measures of vitamin K status (plasma vitamin K and % undercarboxylated osteocalcin) and apo E genotype were measured in 142 HD patients. Clinical and laboratory data were obtained for these patients by chart review. The average age of the patients was 62.6 years, and their vitamin K status using either biochemical marker was low compared to healthy adults. In this population, 17% had the apoE4 allele. Using one measure of vitamin K status, there was poorer vitamin K status in those with the apoE4 allele compared to those without this allele. These data indicate suboptimal vitamin K status in HD patients, with some influence of the apolipoprotein E gene on vitamin K status in these patients.

Technical Abstract: Subclinical vitamin K deficiency has been increasingly associated with extraosseous calcification in healthy adults. Non-dietary determinants of vitamin K status include apolipoproteinE (apoE) genotype, which is believed to influence vitamin K transport to peripheral tissues. Phylloquinone and %ucOC were measured by HPLC and RIA, respectively, in 142 HD patients. ApoE phenotype was determined by isoelectric focusing of delipidated serum samples followed by western blot analysis. Clinical and laboratory data were obtained by chart review. Mean (+/- SD) age was 62.6 (14.8) y. Mean (±SD) phylloquinone was 0.99 +/- 1.12 nM/L, with 29% of patients < 0.4 nM/L. There were no associations between phylloquinone and %ucOC, or apoE phenotype. There were positive correlations between phylloquinone and total cholesterol (p=0.017), triglycerides (p=0.022) and ionized calcium (p=0.019). There was a negative correlation between phylloquinone and dialysis adequacy (p=0.002). The mean %ucOC was 51.1 +/- 25.8 with 93% of subjects > 20%. There were positive correlations between %ucOC and dialysis vintage (p<0.001), phosphate (p<0.001), PTH (p<0.001), albumin (p=0.035) and ionized calcium (p=0.046). Seventeen percent (17%) were apoE4. The mean +/- SD %ucOC was significantly greater in those with apoE4 (60.1 +/- 28.4 versus 47.8 +/- 24.4; p=0.035). Multiple regression analysis was performed. With phylloquinone forced into the model, the independent predictors of %ucOC were phosphate, dialysis vintage, PTH and apoE4. These data indicate suboptimal vitamin K status in HD patients as demonstrated by low phylloquinone values and high %ucOC concentrations in 29% and 93% of subjects respectively. The apoE4 allele appears to influence osteocalcin '-carboxylation in HD patients.