Anemia, serum vitamin B12, and folic acid in patients with rheumatoid arthritis, psoriatic arthritis, and systemic lupus erythematosus.

Abstract

Although anemia is frequent in inflammatory rheumatic diseases, data regarding vitamin B12 status is scarce. The purpose of this study was to analyze the incidence and nature of B12 and folic acid (FA) deficiencies in a cohort of rheumatic patients with rheumatoid arthritis (RA), psoriatic arthritis (PsA), and systemic lupus erythematosus (SLE). Levels of B12, FA, and parameters of anemia were recovered or examined in 276 outpatients. In those with recent findings of low serum B12 levels, further studies of serum homocysteine (Hcy) and urine methylmalonic acid (MMA) levels were performed. The incidence of anemia was high: 49%, 46%, and 35%, in RA, SLE, and PsA, respectively. Low levels of serum B12 were also frequent (24%), with almost similar occurrence in the three disease groups. Deficiency in FA was rare (<5%). Mean levels of both vitamins did not differ significantly among the three groups. No correlation between serum B12 levels and anemia was found. In the 15 patients with recently detected low B12 levels, Hcy and MMA were evaluated before and following B12 therapy. In ten of them, baseline Hcy levels were high, while MMA was increased in one patient only. Response to B12 administration, i.e., a decrease in Hcy and/or MMA levels, was noticed in four patients only, suggesting that only 26% of the low-serum-B12 patients had true B12 deficiency. The incidences of anemia and decreased serum B12 levels were high in these three groups of rheumatic patients. However, true tissue deficiency seems to be much rarer.