Anaemia — some basics


Dr Ghulam Siddique

Anemia is characterized by reduction in hemoglobin and-red cells which impairs oxygen delivery to the tissues. Adults are considered anemic if there hemoglobin is less than 13.5g/dL in males or less than 12g/dL in females.

It is important to know the basic function of bone marrow which is responsible for blood formation (hematopoeisis or hemopoeisis).

Bone marrow function can be best understood by drawing a simple analogy. Like the root of a plant produces stem which further produces leaves and flowers of plant, marrow acts like a root and produces stem cell which further divided itself or produces precursor cells. These precursors mature towards forming red cells, some white cells like neutrophils and platelets (octopus shaped cells responsible for coagulation). Red cells contain hemoglobin which delivers oxygen to the entire body cells.

Anemia must always be taken seriously otherwise it may gravely affect quality of life.

Hemoglobin deficiency causes reduction in the oxygen level of the body causing symptoms like fatigue, palpitation on exertion and shortness of breath.

Anemia is a symptom of either some primary disorder in hemopoeisis or of a secondary one as a result of some other chronic disorder like failing kidney function, cancer and some autoimmune conditions like lupus.

Anemia may develop primarily as a result of decreased production or increased loss of red blood cells.

Increased loss: Anemia ensues after external and internal bleeding that includes accidental, heavy menstrual, gastrointestinal etc. Another important cause is hemolysis (increased destruction of blood cells in the body) which mostly occurs in spleen and is characterized by its enlargement (splenomegaly). Splenomegaly may be a manifestation of some primary or secondary disorder in our immune system or a part of the paraneoplastic syndrome (a wide range of symptoms and problems associated with a tumour and its radio-chemotherapy). In some cases, the cause of hemolysis may remain unknown.

Decreased production: Anemia may result from due to either deficiency or malabsorption of iron, vitamins (megaloblastic anemia with vitamin B12 or folate defieciency), factor absence like G6PD deficiency or basic organic disorders like myelodysplasia including marrow failure impairing blood formation, kidney failure which reduces erythropoietin (a protein which acts as a growth factor for marrow). Then there are thalasemias which are hereditary disorders affecting haemoglobin synthesis. Aplastic anemia is a characterized by marrow failure in producing red cells and it may deteriorate into a severe form (pancytopenia) where all forms of blood cells are reduced. Pancytopenia may also stem from some autoimmune disorders (immune system aacting against body tissues) like lupus etc.

The precise cause of bone marrow failure (especially due to suppression of cells) is unknown, however prolonged use of some medicines like chloramphenicol, phenylbutazone, sulfonamides, phenytoin, pain killers etc has been associated with it. Direct injury to bone marrow may be caused by radiation, chemotherapy toxins ( like insecticides) or pharmacological agents;.

Drug-induced anemia usually resolves itself in time or with nutritional support.

Another type of anemia is aplastic anemia. In this condition bone marrow become hypoplastic and pancytopenia develops. There are a number of causes of aplastic anemia.

Iron deficiency is the most common cause of anemia worldwide. Apart from circulating red blood cells the iron is stored in human body as ferritin or hemosiderin and in macrophages.

The most important cause of iron deficiency anemia is occult or profuse blood loss, increased iron requirement in pregnancy and lactation, deficiency states or metalيs malabsorption. To maintain adequate iron stores, heavily menstruating women must absorb daily 3-4 mg of iron from food otherwise they will become iron deficient. Normal dietary iron cannot meet these requirements and medicinal iron is needed during pregnancy and lactation. Decreased iron absorption can also cause iron deficiency. Iron supplements, tablets and injections, are chosen by the doctor according to need-and suitability. However, caution must be exercised in initiating treatment with iron supplements as it should be based on strong clinical findings.

Vitamin B12 deficiency and folic acid deficiency can result in anemia. B12 is present in all foods of animal origin, so dietary B12 deficiency is extremely rare and is seen in vegetarians only. The most common cause of B12 deficiency is seen in pernicious anemia, a hereditary disease. Folic acid is present in most fruits and vegetables. By far the most common cause of folic acid deficiency is inadequate dietary intake. Alcoholics, anorectic patients, not eating fresh fruits and vegetables, over cooked food are major reasons of folic acid deficiency.

Investigation:

I. COMPLETE BLOOD COUNT (CBC) gives quantity of hemoglobin, number of white cells and platelets.

II. ERYTHROCYTE SEDIMENTATION RATE (ESR): It is the rate at which red cells (erythrocytes) sediment in a test tube. It is non specific indicator of inflammation.

III. PERIPHERAL BLOOD FILM (PBF): It is the microscopic examination of a blood-stained slide to determine the shape/health blood cells. Though non specific, it is an important indicator of blood and other disease. It does help a doctor evolve possible scenarios. For example, it the cells are normocytic (normal size), noremochromic (normal colour), a doctor can rule out bone marrow failure. Similarly a Microcytic (smaller cells), hypochromic (palour in cells) PBF generally points towards iron deficiency. A Macrocytic picture shows abnormally large red cells found when red cells formation is disordered. They occur in alcohol excess, megaloblastic anaemia or as a consequence of haemolysis. Rouleaux formation is seen in the film when red cells are stacked/clumped groups. They are often an indicator that a patient has a high ESR and are seen in infections, autoimmune conditions etc.

RETICULOCYTE COUNT: Reticulocytes are young red cells released by the marrow into the blood stream and normally they are 0.2-2% of total red cell count. They are oversized and become normal sized mature red cells in 36 to 48 hours. Their presence shows the marrow is actively producing red cells. They are almost absent (less that 0.2%) in aplastic anemia and higher (greater thatn 2%) in a healthy marrow after haemorrhage, haemolysis or when the marrow is active after treatment of deficient patients with vitamins and iron. These four test require only 3 to 5cc blood. An intelligent interpretation of PBF with patientيs history can help a doctor differentiate between simple and complex cases. Complex cases should always be referred to haematologists who must never forget involving other specialists like medical experts, rheumatologists, endocrinolgists etc, as the case may be, in diagnosing and treating the patient.

Courtesy: The News

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