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 people with alchoholism and those with conditions 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. B12 may be ordered with folate, by itself, or with other screening laboratory tests – such as a CMP (Comprehensive metabolic panel) – to help diagnose the cause of neuropathy.
