Pernicious Anaemia (Megaloblastic Anaemia)

Pernicious anaemia is caused by a deficiency of vitamin B12 or folic acid. One of its characteristics is that there are fewer red cells but these are large and packed with haemoglobin. The lifespan of the cells is short and they disintegrate easily; this can lead to a build-up of yellow pigment in the skin (caused by the accumulation of breakdown products of haemoglobin).

A normal diet provides plenty of vitamin B12 but vegetarians who do not eat meat or other animal produce may not get enough of this vitamin. The usual cause of vitamin B12 deficiency in western societies, however, is the stomach's failure to secrete a particular substance called intrinsic factor which is needed for normal absorption of the vitamin in the intestine. Vitamin B12 deficiency can also arise after operations to remove part of the stomach and from other diseases of the stomach or small intestine which cause the inability to absorb this vitamin.

Folic acid is another B-group vitamin present in most kinds of food, but prolonged cooking, particularly in large volumes of water, destroys the vitamin. Folic-acid deficiency is common, particularly in elderly people on a poor diet lacking fresh vegetables and fruit. If the deficiency is severe it causes an anaemia very similar to that caused by vitamin B12 deficiency. Alcoholics are frequently sufferers, partly because of their poor diet and partly because alcohol seems to have an anti-folic-acid action. Infants fed solely on goat's milk may develop 'goat's milk anaemia' which is due to the milk's low folic-acid content. A deficiency of folic acid also usually accompanies scurvy (vitamin C deficiency) since the two vitamins tend to occur in the same foods. Deficiencies may also arise through failure of absorption in some disorders of the intestine, such as coeliac disease and tropical sprue. Anaemia may also occur at times when folic acid is needed in large quantities by the body, for example in pregnancy, in rapidly growing newborn infants, and as a side-effect of serious diseases such as cancer.

Symptoms

Besides fatigue, weakness and pallor, symptoms include depression and a smooth, red, sore tongue. A serious effect may be deterioration of parts of the nervous system, resulting in numbness and tingling in the limbs. 

Treatment

Treatment of pernicious anaemia caused by lack of vitamin B12 consists of regular injections of small amounts of the vitamin for the person's lifetime, and this alone will usually ensure good health. Treatment of folic-acid deficiency involves giving supplements of the vitamin in the short term and improving the diet in the long term.