Severe vitamin B-12 deficiency in a child mimicking thrombotic thrombocytopenic purpura.

We report a case of severe vitamin B-12 deficiency in a child who had a clinical presentation of hemolysis and thrombocytopenia that suggested the diagnosis of thrombotic thrombocytopenic purpura (TTP) and was associated with decreased ADAMTS13 activity. In this report, we review vitamin B-12 deficiency in children, the relationship between ADAMTS13 activity and TTP and discuss other conditions associated with decreased ADAMTS13 activity.