Population reference values for methylmalonic acid (MMA) and its relation with age, race, supplements use, serum creatinine and serum vitamin B‐12 in the post‐folic acid fortification era

Abstract

Serum MMA concentrations indicate tissue vitamin B‐12 deficiency in individuals with normal renal function. The aim of this study was to investigate the relation of serum MMA concentrations with sex, age, race, supplement use, serum creatinine, and serum vitamin B‐12 in the US population using the data from three National Health and Nutrition Examination Survey cycles, 1999‐2000, 2001‐2002, and 2003‐2004 (NHANES 1999‐2004) conducted in the post‐folic acid fortification period (n=18,569). Adjusted mean serum MMA concentrations were significantly higher in women than in men (P<0.033), in Whites than in Blacks and Hispanics (P<0.001), in older persons than in younger persons (P<0.001), and in non‐supplement users than in supplement users (P<0.001). The likelihood of having high serum MMA concentrations (>350 nmol/L) was significantly higher in older persons (=60 y) than in younger persons (<60 y) (OR: 3.82; P<0.0001), in non‐supplement users than in supplement users (OR: 1.81; P<0.0001), in vitamin B‐12 deficient persons (<148 pmol/L) than in vitamin B‐12 sufficient persons (=148 pmol/L) (OR: 13.8; P<0.0001), and in person with high serum creatinine (=115 µmol/L) than in persons with low serum creatinine (<115 µmol/L) (OR: 10.63; P<0.0001). Vitamin B‐12 status, kidney function, age, race, and supplement use were significant determinants of serum MMA concentrations in the post‐folic acid fortification period.