25-Hydroxyvitamin D Deficiency and Inflammation and Their Association with Hemoglobin Levels in Chronic Kidney Disease

Abstract

Background/Aims: There is limited information about the association of anemia with 25-hydroxyvitamin D [25(OH)D] deficiency and inflammation in the setting of decreased kidney function in the general population. Methods: We examined the association that anemia has with 25(OH)D deficiency and inflammation among 16,301 participants in the Third National Health and Nutrition Examination Survey (NHANES III). Measures of kidney function were estimated glomerular filtration rate (GFR) by using the Modification of Diet in Renal Disease equation. Results: The age-adjusted prevalence of anemia (hemoglobin <12 g/dl) at an estimated GFR of 59–30 ml/min/1.73 m² was 17% increasing to 56% for those participants with an estimated GFR <30 ml/min/1.73 m², while the age-adjusted prevalence of elevated C-reactive protein (CRP >0.21 mg/dl) and reduced 25(OH)D (<20 ng/ml) was 50 and 30%, respectively. After adjusting for demographics, comorbidities and laboratory results, 25(OH)D <20 ng/ml (OR: 1.17; 95% CI: 1.03–1.32; p = 0.014) and log CRP (OR: 3.63; 95% CI: 2.4–5.48 per unit increase of log CRP; p < 0.0001) were associated with hemoglobin levels <12 g/dl. Conclusion: This study provides evidence that lower 25(OH)D and higher CRP levels are independently associated with lower hemoglobin concentrations in kidney disease subjects not requiring dialysis.