Lesson Objectives Upon completion of this lesson, students should be able to: 1.Define and spell the terms to learn for this chapter. 2.List the components of blood, including the liquid and cellular portions and functions of each. 3.Describe causes and implications for each of the blood tests discussed.

Lesson Objectives Upon completion of this lesson, students should be able to: 4.Discuss the variables that can affect the accuracy of laboratory test results. 5.Explain how hematology is used to diagnose and treat disease.

Lesson Objectives Upon completion of this lesson, students should be able to: 6.Identify frequently used blood and blood chemistry tests and describe proper patient preparation for each. 7.State the normal values for each of the blood tests discussed and identify critical values to report immediately.

Hematology The study of blood and the tissues that produce it Lab tests performed on blood are commonly used to verify or rule out a suspected diagnosis. Blood analysis is one of the most common diagnostic tools in the doctor's office.

The Medical Assistant's Role MA collects the specimen MA may also perform laboratory testing within his or her scope of practice MA must know normal values and understand what test results reveal

The Medical Assistant's Role Blood Specimen Collection – Strictly regulated by OSHA – Follow CDC standard precautions at all times.

The Medical Assistant's Role Blood Specimen Collection – Laboratories must adhere to CLIA standards; MA must follow regulation guidelines – Refer to Chapter 47 regarding equipment and procedures for blood collection.

Blood Function, Formation, and Components Main functions of the blood are transportation and protection – Blood takes oxygen and nutrients to the body and removes carbon dioxide. – Blood takes waste products to the lungs, liver, kidneys, and skin for elimination.

Blood Function, Formation, and Components Main functions of the blood are transportation and protection – Blood carries white blood cells to help fight off infection and contains platelets to begin the healing process. – Blood assists in regulating body temperature.

Blood Function, Formation, and Components Plasma – Liquid component of blood – Makes up about 55 % of the composition of blood – Carries blood cells and other substances to the different parts of the body

Blood Function, Formation, and Components Plasma – Key component of plasma is fibrinogen – Serum is plasma without the fibrinogen. – 99% of plasma is water; the other 10 % is solid substances that dissolve in the plasma.

Blood Function, Formation, and Components Cellular Components (Formed Elements) – The formation of blood cells is called hematopoiesis. – Blood cells originate from the hematopoietic stem cell, but mature into one of seven individual types of cells.

Critical Thinking Question 1.Where does hematopoiesis primarily occur in adults?

Blood Function, Formation, and Components Red blood cells (erythrocytes) – Transportation of oxygen and carbon dioxide

Blood Function, Formation, and Components White blood cells (leukocytes) – Defense – five types: Granular leukocytes – Neutrophils – Eosinophils – Basophils

Blood Function, Formation, and Components White blood cells (leukocytes) – Defense – five types: Nongranular leukocytes – Lymphocytes – Monocytes

Blood Function, Formation, and Components Platelets (thrombocytes) – Clotting – Although hematopoiesis occurs primarily in the bone marrow of the adult, lymphocytes are also produced in the lymph nodes.

Formed Elements and Associated Tests Blood tests ordered individually or in groups – Referred to as panels, profiles, or counts

Formed Elements and Associated Tests CBC is one of the most common combinations of tests routinely ordered – Includes red blood cell (RBC) counts, RBC indices, hemoglobin (Hgb), hematocrit (Hct), white blood cell (WBC) counts (with or without differential), platelet counts, and blood cell morphology

Formed Elements and Associated Tests Red Blood Cells and Red Blood Cell Tests – (RBCs) or erythrocytes: vessels that carry hemoglobin throughout the body.

Formed Elements and Associated Tests Red Blood Cells and Red Blood Cell Tests – Hemoglobin A vital protein molecule found in red blood cells that has two primary functions Carry oxygen from lungs to cells of the body

Formed Elements and Associated Tests Red Blood Cells and Red Blood Cell Tests – Hemoglobin Carry carbon dioxide from throughout the body back to the lungs where it can be expelled with exhalation

FIGURE 48-2 Red cells have a biconcave shape.

Formed Elements and Associated Tests Erythrocyte or Red Blood Cell (RBC) Count – RBC count is the number of red blood cells per cubic millimeter (mm3) of blood

Formed Elements and Associated Tests Erythrocyte or Red Blood Cell (RBC) Count – Normal values vary according to age and gender Normal RBC range for a male adult is 4.5 to 6 million/mm3 Normal female RBC range is 4 to 5.5 million/mm3, although it may slightly decrease during pregnancy

Formed Elements and Associated Tests Erythrocyte or Red Blood Cell (RBC) Count – Formation of RBCs is controlled somewhat by erythropoietin – Erythropoietin secreted by the kidneys in an adult and by the liver in a fetus

Formed Elements and Associated Tests Erythrocyte or Red Blood Cell (RBC) Count – Hypoxemia The kidneys typically compensate by secreting extra erythropoietin, which in turn stimulates the bone marrow to produce more red blood cells

Formed Elements and Associated Tests Erythrocyte or Red Blood Cell (RBC) Count – Anemia A condition in which the blood has a lower than normal level of red blood cells or of hemoglobin within the red blood cells

Formed Elements and Associated Tests Erythrocyte or Red Blood Cell (RBC) Count – Polycythemia A condition in which the blood has a higher than normal level of red blood cells

Formed Elements and Associated Tests Erythrocyte or Red Blood Cell (RBC) Count – Manual RBC count requires small samples of the blood specimen to be diluted in a special solution, which is added to hemocytometer

Formed Elements and Associated Tests Erythrocyte or Red Blood Cell (RBC) Count – Hemocytometer is placed on a microscope used to count the cells – Test is not considered CLIA-waived – More specific training is required before MA can perform this test in a medical laboratory.

Formed Elements and Associated Tests Reticulocyte Count – The percentage of reticulocytes in the blood in relation to the number of mature RBCs – RBCs last for about four months and are continuously being reproduced in the body – Reticulocytes generally mature within 48 hours.

Formed Elements and Associated Tests Reticulocyte Count – Helps to determine the ability of the bone marrow to compensate for RBC loss – Often used to monitor the response to treatment for anemia

Formed Elements and Associated Tests Reticulocyte Count – Increased rates typical in pregnancy, newborns, high altitudes, and stimulated red blood cell production – Decreased reticulocytes noted in renal or bone marrow disease, use of certain drugs, aplastic anemia, alcoholism, folic acid deficiency, and transfusions

Formed Elements and Associated Tests Hemoglobin (Hgb) – Red blood cells contain hemoglobin – Consists of iron (heme) and a protein (globulin) – Hemoglobin in the blood is responsible for carrying oxygen throughout the body.

Formed Elements and Associated Tests Hemoglobin (Hgb) – Higher Hgb levels The body is able to transport more oxygen – Lower levels Less oxygen is in circulation – Normal values for adult females are 12– 16 g/dL and for males 14–18 g/dL.

Formed Elements and Associated Tests Hemoglobin (Hgb) – Measured by an automated blood analyzer or manually by a hemoglobinometer – Manual calculations are not CLIA- waived.

Formed Elements and Associated Tests Hemoglobin (Hgb) – Values can be determined by the specific gravity method or the cyanmethemoglobin method. – Abnormal levels can be dangerous because they affect the level of oxygen available to the cells.

FIGURE 48-4 Hemoglobinometer (manual blood analyzer).

FIGURE 48-5 Automated blood analyzer. Nicram Sabod/Shutterstock

Formed Elements and Associated Tests Hemoglobin (Hgb) – Hemolytic disorders, cancers, anemias, sickle cell disease, thalassemia, frequent blood draws or loss, fluid retention, and pregnancy can lower Hgb levels – Hgb less than 5 g/dL is considered to be a critical value; report to physician immediately

Formed Elements and Associated Tests Hemoglobin (Hgb) – Hgb over 20 g/dLo can lead to blood clots from increased concentration; considered critical

Determining Hemoglobin Using the Hemoglobinometer Refer to Procedure 48-1 in the student text for detailed instructions in this technique. – Note: This test is typically not performed by a medical assistant in a medical office setting.

Formed Elements and Associated Tests Hematocrit (Hct) – Hct test evaluates the percentage of packed red blood cells in the total volume of blood – In a patient with normal RBC and Hgb levels, the approximate hematocrit should be about three times the hemoglobin level. Normal hematocrit is 40 to 50 % in males and 35 to 45 % in females

Formed Elements and Associated Tests Hematocrit (Hct) – Low hematocrit may indicate anemia or hemorrhage. – Elevated hematocrit may indicate dehydration or polycythemia.

Formed Elements and Associated Tests Hematocrit (Hct) – High glucose levels may falsely indicate elevated hematocrit levels. – The microhematocrit, or "crit," is a hematocrit performed on an extremely small quantity of blood collected in a capillary tube.

FIGURE 48-7 The hematocrit.

FIGURE 48-8 Hematocrits, left to right: normal, anemia, polycythemia.

FIGURE 48-9 A microhematocrit.

Performing a Microhematocrit 1.Perform hand hygiene and apply gloves. 2.Assemble equipment. 3.Fill two capillary tubes three- quarters full. The blood specimen can be obtained from a vacuum tube of anticoagulated blood using a plain capillary tube or directly from a finger-stick site using a heparinized capillary tube. Seal one end in the sealing clay.

PROCEDURE 48-2 Performing a Microhematocrit FIGURE A Centrifuge and supplies.

Performing a Microhematocrit 4.Place capillary tubes in the centrifuge with the sealed ends against the rubber gasket. If more than one patient's blood is being tested, mark down the number of the slot the patient's tube is in. Spin for three to five minutes at 10,000 rpm. (Always check the manufacturer's recommendations for proper time and speed.) After centrifuging, the sample will be separated into three layers.

PROCEDURE 48-2 (continued) Performing a Microhematocrit FIGURE B Loading a centrifuge. Suthep/Shutterstock

Performing a Microhematocrit 5.Remove tubes immediately after centrifuge stops. If tubes are not removed immediately, blood may begin to mix together.

Performing a Microhematocrit 6.Determine the results. Use the Hct card by placing the sealing clay just below the zero line on both tubes. Then, on both tubes, match the top of the plasma with the 100 line. Read results on both tubes directly below the buffy coat. Then add those results together and divide by 2.

Performing a Microhematocrit 7.Discard the tubes into the sharps container 8.Remove gloves and perform hand hygiene 9.Record the value as a percentage on the patient's medical record.

Formed Elements and Associated Tests Erythrocyte/RBC Indices – Help to differentiate the type of anemia present by indicating the size of RBCs and the concentration of Hgb – Mean corpuscular volume (MCV) measures the average size of RBCs and classifies them according to size – Mean corpuscular hemoglobin (MCH) measures the average amount of hemoglobin in a red blood cell

Formed Elements and Associated Tests Erythrocyte/RBC Indices – Mean corpuscular hemoglobin concentration (MCHC) measures the amount of hemoglobin relative to the size of the cell – When MCV, MCH, and MCHC are decreased, iron deficiency anemia is likely

Formed Elements and Associated Tests Erythrocyte/RBC Indices – When MCV, MCH, and MCHC are increased, vitamin B12 or folic acid deficiency is likely

Formed Elements and Associated Tests Erythrocyte Sedimentation Rate (ESR) – Also called "sed rate" – Evaluates red blood cells – Determines the rate at which RBCs settle at the bottom of a tube

Formed Elements and Associated Tests Erythrocyte Sedimentation Rate (ESR) – Related to the condition of the RBCs and the amount of fibrinogen in the plasma – RBCs that fall at a faster than normal rate can indicate the possible existence of conditions associated with increased fibrinogen.

Formed Elements and Associated Tests Erythrocyte Sedimentation Rate (ESR) – Not diagnostic; used in conjunction with other tests to determine a diagnosis – Done using either the Wintrobe or the Westergren method

Formed Elements and Associated Tests Erythrocyte Sedimentation Rate (ESR) – Increased values may suggest inflammation. – ESR may also be elevated because of menstruation, pregnancy, and the use of specific medications.

Performing an ESR Test Using the Wintrobe Tube Method 1.Perform hand hygiene and apply gloves. 2.Assemble equipment. 3.Obtain a whole-blood sample using a purple-top tube. Mix well. EDTA is the anticoagulant of choice. 4.Slowly fill Wintrobe tube with blood. Avoid air bubbles.

Performing an ESR Test Using the Wintrobe Tube Method 5.Adjust the meniscus of the specimen to the zero line at the top of the tube. 6.Maintain the tube in an upright vertical position for one hour.

Performing an ESR Test Using the Wintrobe Tube Method 7.After one hour, record the number of RBCs that settle. Read the ESR on the same side of the tube as the zero line at the top. 8.Remove gloves and perform hand hygiene. 9.Record the procedure on the patient's medical record.