B12 and Folate (Folic Acid, Vitamin B9) are mainly ordered to help diagnose the cause of macrocytic anemia. 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 conditions associated with malabsorption such as Crohn’s disease, celiac disease, and cystic fibrosis. Folate and B12 may also be ordered to help diagnose the cause of mental or behavioral changes, especially in the elderly. B12 may be ordered by itself, with folate, or with other screening laboratory tests – such as a CMP (comprehensive metabolic panel) – in order diagnose the cause of neuropathy. In those with known B12 and folate deficiencies, these tests may be ordered occasionally to help monitor the effectiveness of treatment. This is especially true in those who cannot absorb B12 and/or folate and must have lifelong treatment. They are ordered as follow-up tests when large RBCs and a decreased hemoglobin concentration are found during a CBC test.