complete blood count (cbc)
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DESCRIPTIONComplete Blood Count (CBC). Complete Blood Count (CBC). Panel of tests that examine different components of the blood. CBC values RBC count Hemoglobin Hematocrit RBC indices WBC count and differential Platelet count. - PowerPoint PPT Presentation
Complete Blood Count (CBC)Panel of tests that examine different components of the blood.CBC valuesRBC count HemoglobinHematocritRBC indicesWBC count and differentialPlatelet count
White Blood Count (WBC): actual number of white blood cells per volume of blood.WBC differential: types of WBC present.
Red Blood Cells (RBC): actual number of red blood cells per volume of blood
Hemoglobin (Hb): amount of the oxygen carrying protein in the blood Platelets (PLT): actual number of platelets per volume of blood
Mean Corpuscular Volume (MCV ): a measurement of the average size of RBCs Mean Corpuscular Hemoglobin (MCH ): the average amount of oxygen-carrying hemoglobin inside a RBC Mean Corpuscular Hemoglobin Concentration (MCHC): the average concentration of hemoglobin inside a RBC
Red Cell Distribution Width (RDW): a variation in the size of RBCs
The significance of CBCFind the cause of symptoms such as fatigue, weakness, fever, bruising, or weight lossDiagnosis of anemiaEstimation of blood lossDiagnosis of polycythemiaFind an infectionDiagnosis of blood diseases as leukemiaResponse to drug or radiation treatmentScreening before surgeryAbnormal count of certain types of cells
PrincipleThe counting of the cellular elements of the blood (erythrocytes, leukocytes, and platelets) is based on the classic method of electrical impedance. Electrical resistant principle, which depend on the fact that blood cells are non conductive to electricity, so when they pass through electrical field they will increase the electrical resistance. The counting chamber consists of a beaker, two electrodes with a direct current, an orifice with specified dimension; when suspended cells passes through the aperture it will increase the electrical impedance between the two electrodes, manifested as a pulse (sum of pulse= count). The pulse height indicate cell volume.
PerformanceThe aspirated whole blood specimen is divided into two aliquots and mixed with an isotonic diluent.The first dilution is delivered to the RBC aperture bath, and the second is delivered to the WBC aperture bath. In the RBC chamber, both the RBCs and the platelets are counted and discriminated by electrical impedance Particles between 2 and 20 fL are counted as platelets, and those greater than 36 fL are counted as RBCs. Red cell histograms: histograms are derived by plotting the size of each red cell on x axis and the relative number on the y axis. They are used to determine the average size, distribution of size, and to detect sub populations.
Hb measurementA reagent to lyse RBCs and release hemoglobin is added to the WBC dilution before the WBCs are counted by impedance After the counting cycles are complete, the WBC dilution is passed to the hemoglobinometer for hemoglobin determination (light transmittance read at a wavelength of 535 nm). Hemoglobin, on most automated systems, is measured as cyanmethemoglobin. Red cells are lysed and potassium ferricyanide oxidizes hemoglobin to methemoglobin, which combines with potassium cyanide forming cyanmethemoglobin. The brown color is measured spectrophotometrically and the corresponding hemoglobin reported.Normal rangMales 14-18 g/dlFemales 12-16 g/dl
Normal blood contains about 15-16 grams hemoglobin per 100 ml (dL).
Each gram of hemoglobin can carry about 1.35 ml of gaseous oxygen.
Fully saturated arterial blood will therefore contain about 20 ml of oxygen per 100 cc.
The relative amount of oxygen in the blood compared to the carrying capacity of the hemoglobin is called the oxygen saturation, and is expressed as a percentage.
Hematocrit Hematocrit is the volume of the red cells as compared to the volume of the whole blood sample.
Hematocrits on the automated systems are calculated. Calculated: (MCV)(RBC) = Hct
Usually expressed in percentage (42%) Males 42-52 %Females 37-47% (pregnant>33%)
Provides information on the amount of red blood cells (RBC) present in the blood.
Decreased levels means anemia from hemorrhage, parasites, nutritional deficiencies or chronic disease process, such as liver disease, cancer, etc.
Increased levels are often seen in dehydration or polycythemia
Red Blood Cell Count (RBC)Normal value = 4.6 to 6.2 x 106 cells/L
Decreased with anemia
Increased with erythrocytotic states such as polycythemia vera, erythrocytosis of chronic hypoxia, dehydration, stress polycythemia, and thalassemia minor.
MCVMean cell volumeMCV is average size of RBCMCV = Hct x 10 RBC (millions) If 80-100 fL, normal range, RBCs considered NormocyticIf < 80 fL are MicrocyticIf > 100 fL are Macrocytic
Not reliable when have marked anisocytosis
MCHMCH is average weight of hemoglobin per RBC.
MCH = Hgb x 10 RBC (millions)
MCHCMCHC is average hemoglobin concentration per RBC MCHC = Hgb x 100 Hct (%) If MCHC is normal, cell described as Normochromic If MCHC is less than normal, cell described as Hypochromic There are no Hyperchromic RBCs
RDWAn index of RBC size variationMay be used to quantitate the amount of anisocytosis on peripheral blood smearNormal range is 11.5% to 14.5% for both men and women.MPV: The MPV is a measure of the average volume of platelets in a sample and is analogous to the erythrocytic MCV.Pct : analogues to HCT for RBCs
Use of RBC indices in differential diagnosis can provide picture of what is occurring clinically.
If anemia caused be bone marrow failure, requires information about RBC production. Information obtained from reticulocyte count. Reticulocyte count measures effective RBC production.
As study different anemias, will learn morphology.
Red Cells HistogramNoramal red cell histogrem dispays cells form (36- 360 ) fl
(24- 36 fl ) flag may be due 1- RBCs fragments 2- WBCs fragments 3- Giant plts 4- Microcyte
Shift to right : - Leukemia - Macrocytic anemia - Megaloblastic anemia Shift to left : - Microcyic anemia (IDA)Bimodal - Cold agglutinin - IDA, megaloblastic anemia with transfusion. -Saidroblastic anemia.Trimodal Anemia with transfusion
Platelet CountNormal Range = 150 to 450 x 103 cells/LThrombocytosisinflammatory disordersmyeloproliferative statesacute blood losshemolytic anemiascarcinomatosisstatus post-splenectomyexercise etc.
ThrombocytopeniaProduction defects such as aplastic anemia, marrow replacement, megaloblastic and severe iron deficiency anemias, uremia etc.Consumption defects with autoimmune thrombocytopenias, DIC, hypersplenism, massive hemorrhage and many severe infections.
Plts histogramNormal Rang (2-20 fl) (0-2) 1- Air Babbles 2- Dust Over 20 fl 1- Microcyte 2- Scishtocyte 3- WBCs fragments 4- Giant Plts 5- Clumped plts
ReticulocytesUseful in determining response and potential of bone marrow. Reticulocytes are non-nucleated RBCs that still contain RNA. Visualized by staining with supravital dyes, including new methylene blue; RNA is precipitated as dye-protein complex. Normal range is 0.5-2.0% of all erythrocytes. If bone marrow responding to anemia, should see increases in Retic count. Newborns have higher Retic count than adults until second or third week of life.
Sickle cells (Dreprnocytes)
A variation in erythrocyte distribution such as rouleaux formation or agglutination
White Blood Cell Count (WBC)The white blood cell differential count determines the number of each type of white blood cell, present in the blood.It can be expressed as a percentage (relative numbers of each type of WBC in relationship to the total WBC) or as an absolute value (percentage x total WBC). Of these, the absolute value is much more important than the relative value.There are five basic white blood cell types:Neutrophils Eosinophils Basophils Lymphocytes Monocytes
Each WBC cell type has its' own unique features.
NeutrophilsPolymorphonuclear NeutrophilsThese are the most common of the WBCs and serve as the primary defense against infection. The typical response to infection or serious injury is an increased production of neutrophils.
Bands/StabsEarly in the response to infection, immature forms of neutrophils will be seen. These are call Stab or Band cells. The presence of these immature cells is called a "shift to the left" and can be the earliest sign of a WBC response, even before the WBC becomes elevated.
EosinophilsThese cells play a role in allergic disorders and in combating parasitic infections.Elevations in eosinophil counts are associated with:Allergic reactions Parasite infections Chronic skin infections Some cancers Decreases in eosinophil counts are associated with:Stress Steroid exposure Anything that may suppress WBC production generally
Basophils These cells can digest bacteria and other foreign bodies (phagocytosis) and also have some role in allergic reactions.Elevations in basophil counts are associated with:Some cancers Some allergic reactions Some infections Radiation exposure Diminished basophil counts are associated with:Stress reactions Some allergic reactions Hyperthyroidism Prolonged steroid expo
MonocytesThese cells respond to inflammation, infection and foreign bodies by ingesting and digesting the foreign material.Increased monocyte counts are associated with:Recovery from an acute infection Viral illness Parasitic infections Collagen disease Some cancers Decreased monocyte counts are associated with:HIV infection Rheumatoid arthritis Steroid exp