August 11, 2010, 8:51 pm

Life-giving blood is an essential and integral component of the human body. Human blood consists of cellular components known commonly as red cells, white cells and platelets together with a fluid component known as plasma. the red cells contain haemoglobin which is the principal carrier of oxygen and carbon dioxide in the body. there is a highly refined mechanism by which the red cell haemoglobin is empowered to carry out these functions. Red cells are mainly formed within the bone marrow and several different materials are necessary for their formation. These include proper nourishment, particularly proteins, iron, folic acid and several other vitamins. some hormones are also needed for proper production of blood. the integrity and normal functioning of bone marrow which is the soft, spongy tissue inside bones that makes new blood cells, is essential for the production of normal red cells. An adequate and normal amount of blood, both in quantity and adequacy of its essential components, is a mandatory requirement for good health.

When either the number of red cells are reduced or the haemoglobin content of the red cells go down, a state of anaemia is said to be present. Anaemia is one of the more common blood disorders and it can lead to many health problems. Anemia can be caused by several different basic mechanisms. These can be very broadly classified into three separate groups. These are :-

1. Acute or chronic blood loss

2. Inadequate production of red blood cells and / or of haemoglobin

3. Excessive destruction of red blood cells

From another angle, among many other causes, anaemia can also result from inherited disorders, nutritional problems such as an iron or vitamin deficiency, infections, some kinds of cancer or exposure to certain drugs or toxins.

Blood loss can cause anaemia. Blood may be lost acutely due to excessive bleeding secondary to injury, surgery or a problem with the clotting ability of blood which leads to unusual and sustained bleeding from many sites. Slower, long-term blood loss, such as due to intestinal bleeding from hook worm infestations, peptic ulcers or from inflammatory bowel diseases is also known to cause anaemia. it could also be caused by heavy menstrual losses in adolescent girls. A secondary effect of any form of blood loss is an increase in the body’s need for iron, folic acid and other ingredients which are needed to make new red blood cells. If the intake of these nutrients is sub-optimal, then the anaemia due to loss of blood will be potentiated and made worse by the inability of the body to make good the losses and replenish the required amounts of red cells.

Anaemia caused by inadequate production of the required amounts of blood is primarily due to a failure of the bone marrow to function normally. Bone marrow functional disturbances could be produced by certain viral infections, exposure to several toxic chemicals, radiation or medications and in rare cases to a congenital disturbance of the bone marrow. some childhood cancers can also lead to bone marrow problems. In these situations, the marrow is not able to respond to the need to produce more red cells.

Anaemia also occurs when the body is not able to produce enough healthy red cells because of a deficiency of an essential component that is required for the process to be carried out normally. one such important cause is iron deficiency. Iron is essential for haemoglobin production. Poor dietary iron intake or excessive losses of iron from the body can lead to iron deficiency anaemia, which is perhaps the most common cause of anaemia in children. Iron deficiency anaemia can affect children of any age but is most common in those younger than 2 years old. Girls going through puberty also have a particularly high risk for iron deficiency anaemia because of the onset of menstruation, the monthly blood losses increasing the amount of iron they need to consume in their diets.

Anaemia is also known to occur when red blood cells are being destroyed prematurely. These anaemias are collectively referred to as haemolytic anaemia. the normal lifespan of a red blood cell is around 120 days. once they are beyond their useful life, they are destroyed within the body and fresh red cells are produced to replenish the destroyed ones. In all forms of haemolytic anaemias, this life span is shortened, sometimes quite drastically. when such premature destruction occurs, the bone marrow is overwhelmed by the demand to make new red cells and it cannot keep up with the body’s demand for excessive production of red cells. there are several different types of such haemolytic anaemias and the much discussed thalassaemia too falls into this group. Thalassaemia major is a severe form of anaemia in which the red blood cells are rapidly destroyed and iron liberated from this process is deposited in the skin and vital organs. such abnormal depositions of iron are intensely toxic to the tissues in which it is deposited and this leads to damage to many organs of the body. Thalassaemia minor involves only mild anaemia and minimal red blood cell changes. there are other types of anaemias due to shortening of the lifespan of the red cells such as sickle cell anaemia, hereditary spherocytosis and some enzyme deficiencies in the red blood cells. In one particular type of haemolytic anaemia, due to the production of certain types of antibodies, the immune system mistakes red blood cells for foreign invaders and begins destroying them. this can occur acutely and the process can be triggered by many provoking factors. some of these forms of all these haemolytic anaemia could be quite severe with the haemoglobin levels falling to very low levels at regular intervals. the only way to keep the haemoglobin at satisfactory levels is to administer regular blood transfusions.

In certain chronic diseases such as in some forms of chronic arthritis, tuberculosis and other long standing diseases, anaemia may occur as a complication. In many of these cases there is more than one basic cause for the anaemia. Several different mechanisms such as increase in the rate of destruction, poor replenishment of the red cells and a concomitant deficiency of certain nutritional components may all play a part. In such cases, the anaemia is a symptomatic manifestation of the underlying disease and has a multi-faceted origin.

In acute situations where there has been obvious blood loss, symptoms of a sudden reduction in the circulating blood volume may cause shock and collapse. However, if a child has anaemia which has developed over a period of time, depending on the severity, the symptoms may not be all that florid. the first symptoms might be mild skin paleness and decreased pinkness of the lips and nailbeds. These changes may happen gradually and as such they can be difficult to notice. other common signs include irritability, fatigue, dizziness, lightheadedness, and a rapid heartbeat. If the anaemia is caused by excessive destruction of red cells symptoms may include jaundice which is yellowing of the whites of the eyes, an enlarged spleen, and dark plain tea coloured urine. If the haemoglobin falls to very low levels there may be certain features of heart failure as well. In infants and preschoolers, iron deficiency anaemia can result in developmental delays and behavioural disturbances such as decreased motor activity together with problems of social interaction and attention to tasks. Research indicates that such developmental problems may last into and beyond school age if the iron deficiency is not properly treated.

Clinical assessment of anaemia is not all that accurate unless the anaemia is at least moderately severe. However, in very severe anaemias, the heart is called upon to do extra work to get as much of the reduced amounts of blood to the tissues of the body and this may ultimately result in heart failure. In many cases it is often necessary to run quite a few blood tests to ascertain and assess anaemia. These tests are also helpful in categorising the exact type of anaemia. A complete blood count (CBC) provides a number of parameters that could be used to diagnose the type and severity of anaemia. other diagnostic tests may include:

* Blood smear examination: Blood is smeared on a glass slide for microscopic examination of red cells. this can provide certain types of information regarding the size and shape of red cells.

* Iron tests: These include total serum iron and ferritin tests which can help to determine whether anemia is due to iron deficiency.

* Hemoglobin electrophoresis: this test is used to identify various abnormal haemoglobin types in the blood and to diagnose sickle cell anaemia, the thalassaemias, and other inherited forms of anaemia.

* Bone marrow aspiration and biopsy: this test can help determine whether cell production is happening normally in the bone marrow. it is the only way to diagnose certain types of anaemia where the primary problem is in the bone marrow.

* Reticulocyte count: A measure of young red blood cells which helps to determine if the red cell production is at normal levels.

Treatment for anaemia depends on its cause. it is extremely important not to assume various causes and a definitive diagnosis must first be made before starting treatment. the different laboratory tests help to categorise the nature and severity of anaemia. as it often happens, one may have to progressively increase the tests that are being done, depending on the results of the initial basic investigations. more sophisticated tests are necessary in certain cases as the cause may be quite a complicated one or there may be more than one reason for the anaemia.

Depending on the severity of the anaemia, sometimes urgent treatment may be necessary. If the haemoglobin level is very low and into the range that threatens life, an urgent blood transfusion may be necessary. In certain cases, heart failure complicating severe anaemia needs additional treatment. all types of deficiency anaemias would need appropriate treatment with specific substances that are in short supply in the body and are the root cause of the problem. such replenishment therapy may need drugs to be given for a prolonged period of time, possibly for a few months.

Although children often tolerate anaemia much better than adults, they too need special care when they are anaemic. In general, a child with significant anaemia may tire more easily than other kids and therefore need to limit activity levels. it is important for the child’s teachers and other caregivers are aware of the condition. With appropriate treatment, several types of anaemic could be cured but inherited diseases such as thalassaemia do not have a true "cure". whether anaemia can be prevented depends on its cause. currently, there is no way to prevent anaemia due to genetic defects affecting the production of red blood cells or haemoglobin. all types of deficiency anaemias, especially those due to mineral deficiencies can be very effectively prevented by attention to detail about the dietary constituents and by providing a well balanced mixed diet.

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