Estimation of P{Y

Abstract

Hematology and Blood Bank Technique 18 HEMATOLOGY AND BLOOD BANK TECHNIQUE Notes codes for the formation of β globin chains is on chromosome 11. In adults, a minor amount of HbA2 (α 2 β 2) is also present and constitutes less than 3.5%. During embryonic and fetal life other different types of hemoglobins predominate. These include Gower-1 (present in early embryonic life), Gower-2 and Hb Portland. After the eighth week of development, embryonic hemoglobins are replaced by Fetal hemoglobin (α 2 β 2). This remains the predominant hemoglobin until after birth and constitutes 50-90% of the total hemoglobin. After birth, it's concentration decreases to less than 2% by 30 weeks of age. HbA is then the predominant hemoglobin. The structure and time of occurrence of various hemoglobins is shown in the table below. Name Structure Present in Adult Hb (HbA) α 2 β2 Adults Fetal Hb (HbF) α 2 γ 2 Fetal life Hb Portland ζ 2 γ 2 Embryonic life Function of Hemoglobin Heme has the ability to bind oxygen reversibly and carry it to tissues. It also facilitates the exchange of carbon dioxide between the lungs and tissues. Thus, hemoglobin functions as the primary medium of exchange of oxygen and carbon dioxide. 3.3 ESTIMATION OF HEMOGLOBIN IN THE LABORATORY Various methods are available for estimation of hemoglobin in the laboratory. I. Methods based on development of color. These are z Sahli's or acid hematin method z Cyanmethemoglobin method z Oxyhemoglobin method z Alkaline hematin method II. Measurement of oxygen combining capacity III. Measurement of iron content