Clinical manifestations of vitamin B12 deficiency. Vitamin B12 deficiency affects multiple systems, and clinical sequelae vary in severity from mild fatigue to severe neurologic impairment. Glossitis presents in up to 25% of people with vitamin B12 deficiency, presenting initially as bright red plaques that may evolve into atrophy of the lingual papillae. Angular stomatitis may also occur (not shown). Neurologic manifestations are caused by progressive demyelination and can include myelopathy (spastic paraparesis, extensor plantar response, and impaired perception of position and vibration), peripheral neuropathy (similar clinical features to those of a cryptogenic sensorimotor polyneuropathy), and (rarely) involvement of the optic nerve. Limb reflexes may be exaggerated, diminished, or absent depending on the relative involvement of the cord. Cognitive dysfunction may also be present. Neuropsychiatric abnormalities may be the earliest and only manifestation of vitamin B12 deficiency. About one-quarter of these patients have no anemia. Vitamin B12 deficiency may be associated with hyperpigmentation of the skin, especially over the dorsum of the hands and feet, with accentuation over the interphalangeal joints and terminal phalanges. Learn more about mucocutaneous changes here.
