Vitamin B12 and peripheral nerve function in elderly adults: 'Functional' B12 deficiency as a confounding variable

摘要

To the Editor: The recent report by Leishear and colleagues makes the important observation that objective measures of peripheral nerve function show greater impairment in elderly adults ( > 70) with poor vitamin B12 status (defined as a serum B12 level <260 pmol/L) than in "normal" elderly adults who are B12 replete.1 These neurological abnormalities were even greater in individuals with low serum B12 levels and high B12-dependent metabolite methylmalonic acid (MMA) levels (>271 nmol/ L). However, peripheral nerve function in the "normal" population was also often impaired, and differences between "normal" individuals and those with a low vitamin B12 levels were generally small. Moreover, 37% to 42% of the participants in these three populations had diabetes mellitus (DM) or impaired fasting glucose values.