Complete 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.
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Complete 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
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 redblood 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 CBC • Find the cause of symptoms such as fatigue, weakness, fever, bruising, or weight loss • Diagnosis of anemia • Estimation of blood loss • Diagnosis of polycythemia • Find an infection • Diagnosis of blood diseases as leukemia • Response to drug or radiation treatment • Screening before surgery • Abnormal count of certain types of cells
Principle • The 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.
Performance • The 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 measurement • A 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 rang • Males 14-18 g/dl • Females 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.
MCV Mean cell volume MCV is average size of RBC MCV = Hct x 10 RBC (millions) If 80-100 fL, normal range, RBCs considered Normocytic If < 80 fL are Microcytic If > 100 fL are Macrocytic Not reliable when have marked anisocytosis
MCH MCH is average weight of hemoglobin per RBC. MCH = Hgb x 10 RBC (millions)
MCHC MCHC 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
RDW An index of RBC size variation May be used to quantitate the amount of anisocytosis on peripheral blood smear Normal 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 Histogram • Noramal red cell histogrem dispays cells form (36- 360 ) fl • (24- 36 fl ) flag may be due1- RBCs fragments2- WBCs fragments 3- Giant plts4- 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. • TrimodalAnemia with transfusion
Platelet Count Normal Range = 150 to 450 x 103 cells/L Thrombocytosis inflammatory disorders myeloproliferative states acute blood loss hemolytic anemias carcinomatosis status post-splenectomy exercise etc.
Thrombocytopenia Production 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 histogram • Normal Rang (2-20 fl)(0-2)1- Air Babbles2- Dust • Over 20 fl1- Microcyte2- Scishtocyte3- WBCs fragments 4- Giant Plts5- Clumped plts
Reticulocytes Useful 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.
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.