[Vitamin B12 deficiency: neurological disease with minimal or no anemia].

3 patients with vitamin B12 deficiency are described (men aged 64 and 67 and a women of 75). All presented with neurological disease; 2 had had severe weight loss. In 1 neither anemia nor macrocytosis was found, while in 2 there was only mild macrocytic anemia, so that the diagnosis was established quite late during the disease. These patients demonstrate that a high index of suspicion is required to diagnose vitamin B12 deficiency when there are only mild or no hematological abnormalities. This is especially important because of the direct relation between time elapsed before therapy and the irreversibility of neurological damage. Of note is the severe weight loss simulating malignant disease that can be the presenting symptom or appear during the course of the disease.