OTHER HEMATOLOGICAL PROCEDURES INTRODUCTION Structure of Hemoglobin Two

OTHER HEMATOLOGICAL PROCEDURES INTRODUCTION

Structure of Hemoglobin Two major components Heme (contains iron) Globin (the protein chain) ○ Hemoglobins are named in accordance with their protein chains ○ i. e. . Hgb A has a different protein chain than Hgb S

Types of Hemoglobin Hgb A 2 Hgb F Abnormal Hgbs Hgb S Hgb C Hgbs D, E, G

Methods of Hgb Determination Specific gravity Estimate of hemoglobin concentration Drop of blood is placed in a copper sulfate solution ○ If drop falls rapidly the S. G. of the blood is greater than that of the copper sulfate ○ Blood that floats or falls slowly has low hgb concentration Used to screen donors

Cyanmethemoglobin Method Colorimetric Based on the ability of hgb to combine with other substances and form pigments Read spectrophotometrically Types of hgb pigments Oxyhemoglobin (oxygen) Carboxyhemoglobin (carbon monoxide) Methemoglobin Sulfhemoglobin (irreversible) Cyanmethemoglobin (produced chemically)

PRINCIPLE Ferrous iron in hgb is oxidized to ferric state to form methemoglobin Methemoglobin combines with cyanide to form a stable colored compound that can be read spetrophotometrically Reagent Drabkins reagent (potassium, sodium, and cyanide)

Automated Methods Hemoglobinometers (Hemocue) Principle RBCs lysed Hgb released and combined with cyanide Measured absorbance of pigment is proportional to hgb Interfering substances Lipemia, high WBC count and RBC abnormalities that prevent lysing of cells

Normal Values • Infants (at birth): 16. 0 -23. 0 g/dl • Childhood (3 months-13 years): 10. 0 -14. 0 g/dl • Adult males: 13. 0 -17. 0 g/dl • Adult females: 12. 0 -16. 0 g/dl

Hematocrit Definition- the volume of RBCs in a given volume of blood Clinical significance Estimate of RBC volume Used with hgb value to assess patient’s oxygen-carrying capability

Manual Hematocrit Capillary tube (anticoagulated whole blood) centrifuged for 5 minute at 10, 000 rpm ○ RBCs and other cells -bottom ○ Plasma-top Percentage is determined special reader is used RBC volume in relation to the total volume of whole blood

Automated Hematocrit Blood is passed through an orifice Individual RBCs pass through an electrical current and cause an impedance change Degree of change is affected by sized of cell Hct is calculated by summing the electronic volume of the RBCs in the patient sample Interfering substance High WBC count, very large platelets, very small RBCs (microcytic)

Normal Values • Infants (at birth): 51 -61% • Childhood: 34 -42% • Adult male: 42 -52% • Adult female: 36 -48%