Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Chapter 41 Hematology.

transcript

Chapter 41

Hematology

Hematologic Tests

• Second most common type of tests performed in POL

• Cellular components of blood affected by changes in organs or tissues of body

• Click here to see an animation

Types of Blood Tests

• Hemoglobin• Hematocrit• White blood cell

(WBC) count• Red blood cell (RBC)

count• Platelet count

• Differential WBC count

• Erythrocyte sedimentation rate (ESR)

• Prothrombin time

Hematologic Tests

• Results of tests provide valuable information for diagnosis, evaluating patient’s progress, or regulating further treatment

Complete Blood Count

• Hemoglobin determination

• Hematocrit determination

• WBC count

Complete Blood Count

• RBC count

• Differential WBC count

• Erythrocyte indices

Hemoglobin and Hematocrit

• Hemoglobin– Major component of erythrocyte and carrier of oxygen

in body; 85 percent of dry weight of RBC

– Synthesis of heme requires iron

– Adult male requires 0.5 mg/day of iron

– Menstruating female requires 2 mg/day of iron

• Hemoglobin– Carries 95 percent of oxygen to cells

– Transports 27 percent of carbon dioxide back to lungs for removal

– Acts as buffer system

• Hematocrit– Separation of blood into liquid portion and solid

portion by process of centrifugation

– Erythropoietin• Hormone that triggers production of new red cells

– Hemoglobinopathies• Group of diseases; abnormal forms of hemoglobin

• Hematocrit– Iron deficiency anemia

• Near-normal hematocrit with low hemoglobin value; hypochromic RBC lack hemoglobin

• Determining hemoglobin values– Cyanmethemoglobin

• Normal hemoglobin values or reference ranges by age or sex

• Normal hematocrit values or reference ranges by age or sex

• Microhematocrit– Centrifuge

– Packed cell column showing separation of cellular components >>

WBC and RBC Counts

• WBC and RBC counts– Automated method

• WBC differential– Normal leukocyte counts

Leukocyte Identification Guide

Leukocyte Differentiation

• Groups– Myelocytic or granulocytic series

– Lymphocytic

– Monocytic

Leukocyte Differentiation

• Granulocytic group– Neutrophil

– Eosinophil

– Basophil

• Differential leukocyte count

• Normal values for a differential leukocyte count in adults

Erythrocyte Indices

• Include:– Mean corpuscular volume (MCV)

– Mean corpuscular hemoglobin (MCH)

– Mean corpuscular hemoglobin concentration (MCHC)

Erythrocyte Indices

• Provide information about size of RBC and hemoglobin content

• Normal values

Erythrocyte Indices

• Using erythrocyte indices to diagnose– MCH and MCV increased in megaloblastic anemias

– MCH and MCV decreased in hypochromic and microcytic anemias

– MCHC increased in hereditary spherocytosis

– MCHC normal in macrocytosis

– MCHC decreased in iron deficiency anemia

Erythrocyte Sedimentation Rate

• Measures rate at which RBC fall toward bottom when placed in vertical tube >>

• Also called “sed rate”

• Used in diagnosis and treatment of many diseases– Inexpensive

– Accurate

– Easy to perform

• Wintrobe method– EDTA venous blood sample mixed

– Blood transferred with Pasteur pipette to Wintrobe tube

– No air bubbles

– Place tube vertically in rack to stand for 60 minutes

– Read number of millimeters red cells settled

– Normal values for Wintrobe method of ESR

• Westergren method– Mix blood sample with 3.8 percent sodium citrate

solution before filling tube

– Normal values for Westergren method of ESR

– Sediplast ESR system

• Guidelines for Wintrobe and Westergren ESR procedures to measure accurate results

Rouleaux >>

• Using the ESR to diagnose– ESR increased in infections and inflammatory diseases,

tissue destruction, and other conditions leading to increased plasma fibrinogen

– ESR increased with anemia, menstruation, pregnancy, malignant neoplasms, and multiple myeloma

– ESR normal in osteoarthritis, some cases of cirrhosis, and malaria

– ESR decreased in polycythemia, spherocytosis, and sickle cell anemia

Coagulation Studies

• Prothrombin Time (PT)– “Protime”

– Measures time it takes a patient’s blood to clot

– Normal blood clots in 11-13 seconds

• International Normalized Ratio (INR)– Can be universally applied

Automated Hematology Instrumentation and Quality Control • Hematology instruments that require

sample dilutions

• Hematology instruments that do not require sample dilutions

Automated Hematology Instrumentation and Quality Control

• CLIA ’88 regulation for quality control in automated hematology

Automated Hematology Instrumentation and Quality Control• Required procedures

– Calibration

– Control samples

– Proficiency testing

• Check manufacturer’s recommendations for particular piece of equipment

Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Chapter 41 Hematology.

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