Polycythaemia is a condition in which there is high concentration of red blood cells in the blood. This means that the blood volume that is occupied by the red blood cell increases. The common symptoms of polycythaemia are blurred vision, chest pain, headaches, itching, muscle pain, dizziness, ruddy complexion, high blood pressure, and tinnitus or ringing in the ear (Ang et al., 2002).
2.8.2 HAEMOGLOBIN (Hb)
Haemoglobin carries oxygen to the t
issues and so being the respiratory pigment of the blood. Its concentration in an animal system is in proportion of the animal to the sustained muscular activities or ability to meet demand for sudden burst of speed (Schaln et al., 2009).
Haemoglobin consists of photoporphynin, native globulin and ferrous ion. The ferrous iron is 3.35mg/g of haemoglobin. This indicates that haemoglobin is an iron containing compound found in the red blood cell, which transports oxygen around the body (Machlus et al., 2014).
By estimating the concentration of haemoglobin in the blood, anaemia can be diagnosed. The measurement may also detect at normal high concentration of haemoglobin. This may occur in higher animal with chronic lung diseases, as an adaptation to high attitudes or because of an abnormal increase in red blood production by the bone marrow (polycythaemia vera) (Schaln et al., 2009). Haemoglobin are lower in women than man, probably due to menstrual loss and influence of hormones on erythropoiesis. Haemoglobin level fall in normal pregnancy due to an increase in plasma volume. Haemoglobin is measured to detect anaemia and its severity and monitor an anaemia patient’s response to treatment. Monitoring the haemoglobin level (PCV) is also required when patient with HIV disease are treated with AZT. The test is also performed to check haemoglobin level of the blood donor prior to donating blood (Yip et al., 2005).
Techniques for measuring Haemoglobin
Depending on available facilities and resources, Haemoglobin is measured photometrically or estimated with the use of a visual comparative technique.
Photometric techniques: In photometric technique, the absorbance of haemoglobin in a blood sample is measured electronically using a filter colorimeter or a direct read out haemoglobin meter. Techniques in this method include dilute technique in which the blood is measure into a measured volume of diluting fluid, and non-diluting techniques which do not require prior dilution of the blood (Fleming et al., 2008).
Visual comparative technique: when it is not measure haemoglobin accurately using a photometric technique, for example in a health centre or antenatal unit, a visual comparative technique such as the haemoglobin colour scale, can help to detect low haemoglobin level and assess its severity.
2.8.3 WHITE BLOOD COUNT
White blood cell is an intrinsic body defence system. They are produced in the bone marrow and carried into the blood cells. When there is no disease condition in an animal or human being there is low production of white blood cell because it white blood cell functions to fight the disease condition. Low level of white blood cells could also result from low production in the bone marrows (Fleming et al., 2000).
Value of Test:
A white blood count (WBC) is used to investigate HIV/AIDS, infections and unexplained fever, and to monitor treatment which can cause leukopenia.
Interpretation of White Blood Count:
Reference ranges for white cell counts vary with age, with higher counts being found in children. There are also gender differences with higher total WBC and neutrophil counts being found in women of child-bearing age and during pregnancy (Yip et al., 2005).
2.8.4 PACKED CELL VOLUME (PCV)
Packed cell volume is derived from the red blood cell (Fleming et al., 2000). Anaemia is reflected when the mean ratio of red blood cell fluid is below normal in the blood or when there is a fall in PCV below the minimum range of the wide species study (in humans, female 36 to 40% and men 45% to 50%). Haemoglobin concentration is the opposite of anaemia which results when packed cell volume exceeds the maximum of the normal range, although decrease of fluid could arise as a result of lowered intake of water or excess loss of water, thereby increasing red blood concentration (Schaln et al., 2009).
Value of Test:
The packed cell volume also known as haematocrit is used to screen for anaemia when it is not possible to measure haemoglobin accurately and mains electricity is available to operate a micro-haematocrit centrifuge. The PCV is also used in the investigation of dehydration, burns, dengue haemorrhagic fever and polycythaemia (Owoyele et al., 2013). In the investigation of anaemia, PCV with haemoglobin value is used to calculate the mean cell haemoglobin concentration (MCHC). Packed cell volume values are reduced in anaemia. Increased values are found when there is loss of plasma as in severe burns, dehydration, in dengue haemorrhagic fever and in all forms of polycythaemia (Berrington et al., 2005).
2.8.5 LYMPHOCYTES
Lymphocytes are of large and small morphology, which are of two types: the B and T forms. The B form is derived from bone marrow and the T form from the thymus. The B form produces antibodies which combines with foreign materials or antigens, while the T form is responsible for the regulation of the antigen and the cell medicated response of the animal (Berrington et al., 2005). Aggregates of lymphocytes are found within the bone marrow of the birds, although major rites of lymphopoiesis in adult rats are located in the spleen, liver, intestines and caecal tensils. An increase in the cell count of lymphocytes is an indication of viral infection (Yip et al., 2005).
Lymphocyte count can be gotten from a differential white cell count or total white cell count. Providing the total white blood cell count is known, the absolute number of lymphocytes can be calculated and an assessment is made on whether the number of the lymphocyte is increased or reduced (compared with the acceptable reference range) (Machlus et al., 2014).
2.8.6 MEAN CORPUSCULAR OR CELL VOLUME (MCV)
Mean cell volume is the expression of the average volume of individual erythrocytes (RBC) calculated with the following formula:
MCV (fematolitres, fl) = (Howlett and Jaime, 2008).
It is useful in determining the type of anaemia an animal or human can have. A low MCV indicates iron deficiency, chronic disease, pregnancy, haemoglobin disorder such as thalassaemia, anaemia due to the blood cell destruction or bone marrow disorder. A high mcv may indicate anaemia due to nutritional deficiencies, bone marrow abnormalities, liver disease, alcoholism, chronic lung disease, or therapy with certain medications (Fowkes, 1996).
There is some variations in reference ranges for mean cell volume values depending on the method used by manufacturers of blood cell analysers to obtain the mean cell volume value and how an instrument has been calibrated. Low mean cell volume values are found in microcytic anaemias particularly iron deficiency, anaemia of chronic diseases and thalassaemia. The MCV is low in infancy (about 70fl at 1 year of age). Raised MCV values are found in macrocytic anaemias, marked reticulocytosis and chronic alcoholism. The mean cell volume is raised in infants (Abbas et al., 2003).
2.8.6 MEAN CELL HAEMOGLOBIN (MCH)
This is the amount of haemoglobin in pictograms in an average red cell. It is the average mass of haemoglobin per red blood cell in a sample of blood. This measure is further guide to the investigation of anaemia. The mean cell haemoglobin is the haemoglobin content of average red blood cell. The mean cell haemoglobin may be low in types of anaemia where the red blood cells are abnormally small, or high in other types of anaemia where the red blood cells are enlarged for example as a result of folic acid or vita B12 deficiency (Abbas et al., 2003). When red cells are hypochromic, the mean cell haemoglobin is reduced and when the red cells are macrocytic, the mean cell haemoglobin is increased. Mean cell haemoglobin is calculated from the haemoglobin and electronically obtained red blood count. A normal value in humans is 27 to 31 picograms/cell.
MCH (picograms) = (Abbas et al., 2003).
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