Anaemia is a particular physical condition in which the amount of haemoglobin in the blood or the number of red blood cells in a person falls below the normal level. More specifically, it is a condition caused by the deficiency of iron in the blood. In fact, haemoglobin is a protein in the red cells that contains iron. It is carried in the red blood cells of the human blood and imparts it the red colour. Haemoglobin makes it possible for the blood to carry oxygen. The body’s tissues need oxygen to function properly. The lack of the minimum amount of red blood cells or haemoglobin would result in a poor oxygen supply to the body and hence people suffering from anaemia look pale and feel tired as they become oxygen-starved.

          In every healthy human being, haemoglobin maintains a certain level of concentration. The mean values of haemoglobin for males are 15 gm per deciliter and for females 13.5 gm per deciliter. Values which are less than 2.5 or 3 standard deviations below the mean value are indicative of anaemia. The mean values are greater for males than for the females and again greater in adults as compared to children.

          To detect anaemia, the concentration of three things in the blood is measured. These are: the haemoglobin, the red-cell count and hematocrit. If the values of these things are below the normal level, the person is said to be anaemic.

          This disease may have several causes. The major ones are: (i) defective blood formation, (ii) cell destruction, and (iii) extensive loss of blood. Moreover there are a number of physical disorders, any of which can cause different types of anaemia. Some of the specific types of anaemia are: (i) microcytic anaemia (red cells are smaller than the normal size), (ii) macrocytic anaemia (red cells are larger than the normal size), (iii) normocytic anaemia (red cells are of normal size), and (iv) hypochromic anaemia (cells contain very little haemoglobin). Anaemia resulting from sudden blood loss are generally normocytic in nature.

          Red cells have an average lifespan of 120 days in the circulation. Each day about 45,000 red cells per microlitre are removed from the blood circulation in a healthy person. They are replaced with new cells from the bone marrow. Anaemia occurs when this rate of removal of red cells from the circulation exceeds the replacement or when the production of red cells is impaired or is ineffective in delivering cells to the circulation. Anaemia also occurs due to the lack of iron in the diet. Some kinds of anaemia can be treated by eating iron-rich foods. Medicines are also available to supply iron required to maintain the desirable level.

          Anaemia which results from the increased red blood cell destruction is known as hemolytic anaemia. This may be caused by poisoning, a kind of malaria, poor diet, allergy or some hereditary condition.