The clinical importance of subnormal folate levels in epileptic patients on anticonvulsant therapy.

A neurological theory was obtained and examination performed on 62 outpatient epileptics on anticonvulsant therapy. Blood counts, folate and B12 assays were performed on all patients and on a control group of 59 adult non-epileptic neurological outpatients. None of the anticonvulsant treated group had clinical peripheral neuropathy; there was one patient with microcytic anaemia and one with normochromic, normocytic anaemia. In 5 of this group the mean corpuscular volume (MCV) was slightly raised but there was no significant overall difference from the control group. In 17 patients serum folate was subnormal and in 7 the red cell folate was subnormal and this was significantly different to the control group (P less than 0.001). Vitamin B12 levels were normal in all subjects. It is concluded that despite subnormal measured folate levels, there is no increased incidence of clinical peripheral neuropathy or of significant macrocytosis. In view of this, we recommend that folate replacement should not be given to non anaemic asymptomatic patients, with subnormal folate levels, on anticonvulsant therapy.