Relationship of serum antioxidant vitamins to serum creatinine in the US population

Several small clinical studies have reported that serum vitamin A levels were higher but serum vitamin C levels were lower among patients with end-stage renal disease. However, the relationship of antioxidant vitamins to renal function has not been studied in the general population. We examined the relationship of serum antioxidant vitamin levels to serum creatinine levels and risk for hypercreatininemia in a representative sample of 6,629 non-Hispanic whites, 4,411 non-Hispanic blacks, and 4,480 Mexican Americans aged 18 years or older who participated in the Third National Health and Nutrition Examination Survey. Serum antioxidant vitamins were measured by isocratic high-performance liquid chromatography, and serum creatinine levels, by the modified kinetic Jaffé method. Serum vitamin A level was positively and significantly associated with serum creatinine level, whereas serum vitamin C level was inversely and significantly associated with serum creatinine level. A one-SD higher level of serum vitamin A (16.9 microg/dL) was associated with a 2.53-fold (95% confidence interval, 1.96 to 3.27; P < 0.001), 2.07-fold (95% confidence interval, 1.84 to 2.33; P < 0.001), and 2.76-fold (95% confidence interval, 1.74 to 4.37; P < 0.001) greater risk for hypercreatininemia among non-Hispanic whites, non-Hispanic blacks, and Mexican Americans, respectively. A one-SD higher serum vitamin C level (0.45 mg/dL) was associated with a 22% (95% confidence interval, 0.06 to 0.35; P = 0.01) and 42% (95% confidence interval, 0.08 to 0.62; P = 0.02) lower risk for hypercreatininemia in non-Hispanic whites and Mexican Americans. Our study provides useful information to support the hypothesis that antioxidant vitamins may have an important role in the pathogenesis of chronic renal failure.