Complete Blood Count (CBC) or Hemogram: This is one of the most common lab tests. It assesses: White blood cells (WBC), WBC Differential, Red blood cells (RBC) and Platelets (PLT). This gives the complete count of blood cells. The blood sample of any individual is collected by venipuncture method by a phlebotomist. The specimen is used to detect WBC count, WBC differential, RBC count, Hemoglobin, Hematocrit, Reticulocyte count, Platelet count.

White blood cells play an important role in immune system. The count of WBC determines that whether our body is completely immunized or not. It is broadly divided into granulocytes and agranulocytes. Granulocytes consists of granular structures like Eosinophils, Basophiles, Neutrophils. Agranulocytes like Monocytes and Lymphocytes havo no granules in them. Normal range of WBC count in adults is 5000 to 10,000/µl. if the WBC count is lower than the normal range, it results in Bone marrow disorder, Autoimmune disorder, Sepsis and Lymphoma. If the count is above the normal range, the results are severe like, bacterial and viral infection, inflammation, Leukemia, Asthma, allergies, tissue death and severe stress. The deviation from the normal range of WBC differentiation count has its own affect as we can see here. Neutrophil count determines the adequate count of neutrophils significant for the human body. The normal range of neutrophil count in men is 3000-7000 mm cube and 1800-7700 mm cube in women. The results of lower count are Sepsis, Autoimmune diseases, Immunodeficiency, Bone marrow damage and adverse drug reactions. The results of higher count are acute bacterial infection, inflammation, tissue death, physiological stress and certain types of Leukemia. Lymphocyte count determines the condition of lymph node. The normal lymphocyte count in men ranges from 1000 to 4000 mm cube and in women it ranges from 1000-4800 mm cube. The lower lymphocyte count leads to autoimmune disorder, infection, bone marrow damage and corticosteroids. The higher lymphocyte count leads to bacterial infection, toxoplasmosis, chronic inflammatory disorder, and lymphocytic leukemia. The normal range of monocytes are 400-600 mm cube in men and 0-800 mm cube in women. The lower monocyte count can cause hairy cell leukemia and bone marrow damage in the human body. The higher monocyte count can cause chronic infection, heart infection, monocytic leukemia and collagen vascular disease. The bilobed eosinophils also has some severe impacts on our body. The normal eosinophil count in men ranges from 50 to 250 mm cube, while in women the count ranges from 0- 450 mm cube. The higher count leads to parasitic infection, inflammatory disorder, asthma, allergies and leukemia. Similarly, the normal basophil count in men and women ranges from 25-100 mm cube. The higher basophil count results in leukemia, inflammation and allergic reactions.

Red blood cells have no nucleus and it is red in color due to the presence of hemoglobin. The life span of RBC is 120 days. The count determines the number of RBC and Hemoglobin. Insufficient number of RBC causes anemia which is very common in Indian women population. The de-shaped or abnormal RBCs also causes many disorders. Excess number of RBC causes erythrocytosis or polycythemia. The normal count of RBC in men ranges from 4500000 to 5500000/µl and 4000000 to 5000000/µl in women. The lower count of RBC results in acute or chronic bleeding, hemolytic anemia, malnutrition, bone marrow disorder, kidney failure and chronic inflammatory disease. The higher RBC count causes dehydration, pulmonary disease, excess erythropoietin and some genetic disorder. The change in shape and morphology of RBC are also dangerous for the proper functioning of the human body. Anisocytosis causes variable sizes of red blood cells. RBCs smaller than 7 µm are referred to as microcytes which causes thalasemia. RBCs larger than 7 µm are called macrocytes which results in B12 deficiency, liver disease and reticulocyte. Poikilocytosis depicts various shapes of red blood cells. Some defective RBC cells have nucleus (nucleated RBC) which causes injury in bone marrow. The red blood cells in the shape of sickle or schizocyte causes sickle cell anaemia which is a genetic disorder. This leads to end-organ damage in the spleen, kidneys and liver. There is no cure for sickle cell disease other than allogenic bone marrow transplant which carries significant risk for morbidity and mortality. The RBC life span increases from 12 to 15 days. The defective morphology like, hypochromasia and ovalocyte causes thalasemia which is an inherited genetic disorders that cause decreased production of normal hemoglobin. The two types of thalassemia are Beta Thalassemia and Alpha Thalassemia. The bone deformities in the face, fatigue, shortness of breath and yellow skin (jaundice) are the symptoms of thalasemia.

Platelets determines the normal clotting of blood. CBC measures number and size of platelets in the human body. Insufficient platelets causes excessive bleeding. The normal range of platelets is 140000 to 400000/µl in the normal adult. The lower count determines viral infection, autoantibody of platelet , cirrhosis, sepsis, autoimmune disease and leukemia. The higher platelet count causes cancer, rheumatoid arthiritis and iron deficiency anemia.

Erythrocyte sedimentation rate (ESR)- is a non-specific test for inflammation. It is easy to perform this test. As it is widely available and inexpensive, it is used widely for screening purposes. It is also used as a monitoring tool for response to treatment in conditions in which it is raised like in the cases of tuberculosis, autoimmune diseases, etc. The ESR test is performed in the laboratory by placing anticoagulated blood in an upright tube for about an hour. The rate of the RBC sedimentation is measured after that. The normal ESR values in mm/hr are listed here as per the age and gender. For men above 50 yrs the normal ESR value is below 20. For men under 50 yrs the normal ESR value is below 15. For women over 50 yrs the normal ESR value is below 30. For women below 50 yrs the normal ESR value is below 20. For newborns the normal ESR value ranges from 0 to 2. For neonatal till puberty the normal ESR value ranges from 3 to 13. ESR is determined by the interaction between factors that promote fibrinogen and resist negative charge of RBCs - that repel each other sedimentation. Normal RBCs settle slowly as they do not form rouleaux or aggragate together. Instead, they gently repel each other due to the negative charge on their surfaces. Increased amount of rouleaux formation contributes to high ESR. Rouleaux are stacks of many RBCs that become heavier and sediment faster. Plasma proteins, especially fibrinogen, adhere to the red cell membranes and neutralize the surface negative charges, promoting cell adherence and rouleaux formation.

For determining ESR, the patient must be kept in fasting for at least 4 hours before testing. The blood sample must be mixed with anticoagulant agent in this test. Mix 0.4 ml sodium citrate with 1.6 ml blood or mix 0.2 ml sodium citrate with 0.8 ml blood. The solutions should be mixed gently without shaking then should be introduced in the graded tube and incubated vertically on the stand for 1 hour. Read the amount of plasma that appeared without moving it and then incubate it for the next hour and read another time. The aggregated RBCs in the rouleaux formation have a higher ratio of 'mass to surface area' as compared to single RBCs and hence it sink faster in the plasma.

In the case where the range of ESR is very high i.e. ESR> 100 mm/hr, the diseases like, multiple myelom, connective tissue disorders (Systemic Lupus Erythromatous, Rheumatoid arthritis and other autoimmune diseases), tuberculosis, malignancies and severe anemicare very prominent. some conditions with low ESR arePolycythemia, Severe Leukocytosis,Sickle cell disease anemia, Hereditary spherocytosis, Congestive cardiac failure, Corticosteroid and Hypofibrinogenemia.

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Geetanjali Murari
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