B12 deficiency is a reduction in vitamin B12 from inadequate dietary intake or impaired absorption. The condition is commonly asymptomatic, but can also present as anemia characterized by enlarged blood corpuscles with characteristic changes in neutrophils, known as megaloblastic anemia.
In serious cases deficiency can potentially cause severe and irreversible damage to the nervous system, including subacute combined degeneration of spinal cord.
...
more
B12 deficiency is a reduction in vitamin B12 from inadequate dietary intake or impaired absorption. The condition is commonly asymptomatic, but can also present as anemia characterized by enlarged blood corpuscles with characteristic changes in neutrophils, known as megaloblastic anemia.
In serious cases deficiency can potentially cause severe and irreversible damage to the nervous system, including subacute combined degeneration of spinal cord.
The anemia is thought to be due to problems in DNA synthesis, specifically in the synthesis of thymine, which is dependent on products of the MTR reaction. Other blood cell types such as white blood cells and platelets are often also low. Bone marrow examination may show megaloblastic hemopoiesis. The anemia responds completely to vitamin B12; the neurological symptoms (if any) respond partly or completely, depending on prior severity and duration.
Early and even fairly pronounced deficiency does not always cause distinct or specific symptoms....
less
