nutritional disorders
Vitamin B12 Deficiency
Symptoms and Signs of Vitamin B12 Deficiency
 Megaloblastic Macrocytic Anemias usually develops insidiously. It is often more severe than its symptoms indicate because its slow evolution allows physiologic adaptation. Occasionally, splenomegaly and hepatomegaly occur. Various gastrointestinal symptoms, including weight loss and poorly localized abdominal pain, may occur. Glossitis, usually described as burning of the tongue, is uncommon. Neurologic symptoms develop independently from and often without hematologic abnormalities. Subacute Combined Degeneration refers to degenerative changes in the nervous system due to vitamin B12 deficiency; they affect mostly brain and spinal cord white matter. Demyelinating or axonal peripheral neuropathies can occur. In early stages, decreased position and vibratory sensation in the extremities is accompanied by mild to moderate weakness and hyporeflexia. In later stages, spasticity, extensor plantar responses, greater loss of position and vibratory sensation in the lower extremities, and ataxia emerge. These deficits may develop in a stocking-glove distribution. Tactile, pain, and temperature sensations are usually spared but may be difficult to assess in older people. Some patients are also irritable and mildly depressed. Paranoia (megaloblastic madness), delirium, confusion, and, at times, postural hypotension may occur in advanced cases. The confusion may be difficult to differentiate from age-related dementias, such as Alzheimer disease. 