Paralysis and pernicious anemia in a young woman.

Vitamin B12 is important for normal nervous system functioning, and deficiencies are associated with various neurological abnormalities. We present a case of an 18-year-old woman who presented with significant neurological sequelae, but only mild hematologic abnormalities and normal vitamin B12 levels. She was found to have a moderately increased mean corpuscular volume, a markedly elevated homocysteine level, and a greatly increased methylmalonic acid level. In symptomatic patients it is important for physicians to maintain a high index of suspicion for B12 deficiency despite normal serum levels. The measurement of MMA and homocysteine levels provides much more sensitive tests, but even these tests do not completely rule out a deficiency. Although, the traditional treatment for vitamin B12 deficiency has been intramuscular cobalamin injections, recent studies have shown that oral cobalamin may be as efficacious.