The Vitamin B12 and Folate Panel measures the levels of two B vitamins, vitamin B12 (cobalamin) and folate (vitamin B9), in the blood serum. Both vitamins are important for making red blood cells, supporting nerve function, and DNA production. This panel combines both measurements because deficiencies in these vitamins can cause similar problems and often need to be evaluated together. This panel is commonly used to help evaluate the cause of certain types of anemia, particularly when red blood cells appear larger than normal. It may also be used to help investigate symptoms such as fatigue, weakness, or nerve-related complaints like tingling or numbness. Testing may be considered for people at higher risk of deficiency, such as those with certain digestive conditions, limited diets, or older adults.