It means that the level of haemoglobin in the blood is lower than that required or the number of red blood cells or their oxygen-carrying capacity is insufficient to meet physiologic needs, which vary by age, sex, altitude, smoking, and pregnancy status. Haemoglobin is important to carry oxygen from the lungs to different parts of the body. Normal value in males is 13.5 to 18 gm% and in females is 12.5 to16 gm%.
Broadly, causes of anemia may be classified as impaired red blood cell (RBC) production; increased RBC destruction (hemolytic anaemias), blood loss and fluid overload (hypervolemia).
Iron deficiency anaemia is the commonest form and results from a shortage of iron from a poor diet, blood loss, illness or infection. Pregnant women are particularly at risk. Pernicious anaemia develops due to lack of intrinsic factor, which is secreted by the stomach which prevents absorption of vitamin B12 required for red blood cell production. It affects vegetarians and group A particularly.
Megaloblastic anaemia results from shortage of folic acid, which is found in fresh vegetables, fruits and liver. This is more seen in elderly people and pregnant women.