Vitamin B12 and folate are primarily requested to help diagnose the cause of macrocytic anaemia. They can be requested as follow-up tests when large red cells and a decreased haemoglobin concentration are found during a FBC test.
Vitamin B12 is an important vitamin, essential for the normal functioning of many body processes. Deficiency can lead to anaemia (poor quality red blood cells) and neurological (nerve) disorders. It is most abundant in meat products so vegetarians are more vulnerable to deficiency of this vitamin. Pernicious anaemia develops if uptake of vitamin B12 into the blood from the gut is absent or severely impaired, and even if a diet rich in the vitamin is taken, deficiency will occur if this disease is present. Recent evidence suggests that mild deficiency is probably more common than previously thought. Mild deficiency may explain the presence of fatigue and a host of other limiting symptoms.