Serum vitamin B12, folate, and homocysteine levels and their association with clinical and electrophysiological parameters in multiple sclerosis.

Patients with multiple sclerosis (MS) may have low serum vitamin B12 and folate levels and high levels of homocysteine. We aimed to evaluate serum vitamin B12, folate, homocysteine, mean corpuscular volume (MCV), hemoglobin (Hb), and hematocrit (Hct) levels in patients with MS. We examined the relationship between these parameters and age, sex, disease type, age at onset, disease duration, Expanded Disability Status Score, immunoglobulin G (IgG) index, oligoclonal band presence, visual evoked potentials (VEP) and posterior tibial somatosensory evoked potentials (SEP). These parameters were evaluated in 35 patients during an acute attack and compared to data collected from 30 healthy individuals (control subjects). Serum vitamin B12, folate, homocysteine, Hb, and Hct levels and MCV were low in a proportion of patients with MS (20%, 14.3%, 20%, 6.7%, 3.3% and 10% respectively), whereas only vitamin B12 and folate levels were low in only 3.3% of the control subjects. Homocysteine levels were high in 20% of patients with MS but were within normal limits in the control group. Elevated Hct levels were significantly correlated (p<0.05) with prolonged posterior tibial SEP P1 and P2 latencies compared to the control subjects. Patients with MS who had prolonged VEP and posterior tibial SEP P1 and P2 latencies also had lower vitamin B12 levels compared to patients with normal latencies. Thus, we found a significant relationship between MS and vitamin B12 deficiency, and also demonstrated a relationship between vitamin B12 deficiency, VEP and posterior tibial SEP in MS.