[Macrocytosis, polyneuropathy and posterior column disorders caused by malabsorption of protein-bound vitamin B12].

This case report concerns a patient with a vitamin B12 deficiency and a normal Schilling test, who had macrocytosis of many years' duration and finally polyneuropathy. All known causes of a vitamin B12 deficiency were excluded. When the Schilling test was performed with egg consumption, excretion of vitamin B12 was clearly diminished. It appears highly likely that this vitamin B12 deficiency developed as a result of malabsorption of protein-bound vitamin B12.