Manual of basic techniques for a health laboratory - libdoc.who.int

288 Manual of basic techniques for a health laboratorysymptoms range from pallor and mild fatigue to headache, dizziness and irritabilityto uncontrolled behaviour and even shock and cardiac insufficiency.Anaemia may result from:— blood loss— decreased production of erythrocytes— increased destruction of erythrocytes.The most common cause of anaemia worldwide is iron deficiency. Other commoncauses such as infection, malaria, malnutrition and vitamin deficiencies usuallycontribute to anaemia in association with iron deficiency. Other causes of anaemiaare:— trauma— parasitic infections— diseases of the endocrine system— chronic diseases— inborn errors of metabolism— intoxication.9.6 Estimation of the leukocyte number concentrationThe number of leukocytes contained in 1 litre of blood is called the leukocytenumber concentration or leukocyte count.In certain diseases the number of leukocytes in the blood is altered. For example,in infectious mononucleosis and bacterial infections there is a marked increase,whereas in typhoid fever there is a marked decrease.9.6.1 PrincipleThe blood is diluted in a leukocyte diluting fluid which haemolyses the erythrocytes,but leaves the leukocytes intact.The leukocytes are then counted in a counting chamber under the microscope, andthe number of cells per litre of blood is calculated.9.6.2 Materials and reagents●●●MicroscopeRuled counting chamber — preferably the improved Neubauer chamber (Fig.9.40; the Bürker chamber is rarely used)Blood (Sahli) pipette, graduated to the 50-ml (0.05-ml) markFig. 9.40 Neubauer counting chamber