Red blood cells are the cells in the blood that are responsible for carrying oxygen to the various organs. The red blood cells carry oxygen by attaching to the hemoglobin molecules. If there is any significant reduction in the blood hemoglobin level, the condition is clinically known as anaemia. A useful approach to anaemia is to understand the normal red cell life span.
Production of red cells begins in the bone marrow with the mother red cells undergoing a maturation process. After the red cells have completed this process, they will be released into the bloodstream. These circulating red cells will remain in the blood for about 120 days before they are destroyed (predominantly in the spleen). Therefore, anaemia could effectively be a problem of production or a loss/destruction.
Red cells in the marrow can be reduced in many ways: eg. by marrow damage (ie. aplasia, infiltration by other tumors, drug induced damage), decreased stimulation (ie. renal disease, certain endocrine disorders), lack of certain nutrients (ie. iron deficiency anaemia , folate deficiency anaemia), some hereditary disorders (ie. thalassemia, sickle cell anaemia, G6PD deficiency, sideroblastic anaemia), etc.
Similarly, acute destruction or loss can likewise reduce the number of red cells in the bloodstream. Since the spleen is the major filter of the red cells, any inappropriate increase in splenic function will result in unusually high destruction of the red cells. Increased splenic function (or hypersplenism) may be caused by a primary splenic disease or secondary to the complications of other disease states. Other major mechanisms for red cell destruction will include infective causes (eg malaria), self-destructive causes (eg autoimmune hemolytic anaemia), hereditary disorders (eg paroxysmal nocturnal hemoglobinuria), and physical agents (eg burns). Furthermore, in any situations where there is significant bleeding, the number of red cells can also decrease accordingly.
Clinically, there are several laboratory tests that can assist the physicians to arrive at a diagnosis. A careful study of the blood film often offers many clues eg. changes in shape/size/colour of the blood cell, any abnormal intracellular inclusions, any parasites or worms present, etc. With these blood features as a guide, the clinician can proceed to other tests for diagnostic confirmation. These confirmatory tests may include a genetic study for certain hereditary disorders, biochemical determination of certain intracellular/extracellular chemical levels such as iron/folate, CT scan of the spleen for possible splenic disorders, bone marrow/lymph node biopsy for malignancies, etc.
Once a diagnosis is made, the aims of management are two-prong i.e. to eliminate the causative factors as well as to restore the red cell functions if possible. This would often necessitate the use of various nutritional supplements, pharmaceutical agents and/or surgical procedures. In certain situations, the physician may even need to restore the red cell functions by giving blood/red cell transfusions.