Association of 25-hydroxyvitamin D with anemia risk in patients scheduled for cardiac surgery.

INTRODUCTION

There is emerging data that vitamin D plays a role in erythropoiesis. Low 25-hydroxyvitamin D (25OHD) levels may therefore be a risk factor for anemia in patients scheduled for cardiac surgery.

METHODS

We investigated 4428 consecutive cardiac surgical patients to determine an association between anemia (hemoglobin concentration <12.5 g/dL, 27.1% of the study cohort) and circulating 25OHD.

RESULTS

In patients with severe vitamin D deficiency (25OHD < 12.5 nm), mean hemoglobin concentrations were 0.80 g/dL lower compared with patients with adequate 25OHD levels (50.0-100 nm). Hemoglobin levels were not significantly different at 25OHD levels above 100 nm compared with 50.0-100 nm. In multivariable-adjusted logistic regression analyses, the odds ratios for anemia of the groups with severe and moderate vitamin D deficiency (12.5-29.9 nm) were 1.70 (95% CI:1.09-2.63) and 1.41 (95% CI:1.02-1.96), respectively, compared with patients who had circulating 25OHD levels of 75-100 nm. Prevalence of deficient circulating 25OHD levels was highest in anemia of chronic kidney disease.

CONCLUSION

This cross-sectional study demonstrates an independent association between vitamin D status and anemia risk with optimal 25OHD levels of 75-100 nm. Randomized controlled trials are needed to clarify whether this association is causal.