More on the test...
B12 and folate are primarily ordered to help diagnose the cause of macrocytic anemia. They are ordered as follow-up tests when large RBCs and a decreased hemoglobin concentration are found during a CBC test. Folate, B12, and an assortment of other tests may be ordered to help evaluate the general health and nutritional status of a patient with signs of significant malnutrition or malabsorption. This may include those with alcoholism and those with disorders associated with malabsorption such as celiac disease, Crohn's disease, and cystic fibrosis. B12 and folate may also be ordered to help diagnose the cause of mental or behavioral changes, especially in the elderly.
Folates are a class of vitamin compounds necessary for nucliec acid mitochondrial protein synthesis; amino acid metabolism and other cellular processes. The predominant form of circulating folate is 5-methyltetrahydrofolic acid (5-m THF), which requires the presence of Vitamin B12 for conversion to the metabolically active folate i.e.,tetrahydrofolate (THF).
Deficincy of B12 prevents cells from producing usable THF which in turn prevents synthesis of purines or thymine for DNA replication, and metabolization of histadine and serine. Thus, primary deficiency of folates, or secondary deficiency of B12 can lead to magloblastic anemia, wherein blood cells cannot divide because they are unable to make DNA.
Folates are derived entirely from diet. Folate deficiency can be caused by low dietry intake, malabsorbtin, inadequate utilization due to enzyme deficiency, folate antagonist therapy (drugs eg .alochol, contraceptives) or excessive demand, eg. pregnancy.
The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions.