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Automated CBC Parameters and Quality Control Joanna Ellis, MLS(ASCP)

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Presentation on theme: "Automated CBC Parameters and Quality Control Joanna Ellis, MLS(ASCP)"— Presentation transcript:

1 Automated CBC Parameters and Quality Control Joanna Ellis, MLS(ASCP)

2 The Automated Complete Blood Count Most common test in the Hematology lab. Main Components of the CBC: – Cell counts – Hgb – RBC indices – WBC differential absolute values and percent Indications for CBC: – Fatigue – Weakness – Infection – Inflammation – Bruising – Bleeding

3 CBC Parameters PARAMETERUNIT OF REPORTINGCOMMON METHOD OF DETERMINATION WBCX 10 3 /µLImpedance count X calibration (cal) factor RBCX 10 6 /µLImpedance count X calibration factor HGBg/dLColorimetric absorbance in proportion to hemoglobin MCVfL From RBC histogram, #of RBCs X size of RBCs X cal constant OR Calculated: HCT X 10 RBC HCT% Calculated: RBC X MCV 10 MCHPg Calculated: HGB X 10 RBC MCHCg/dL or % Calculated: HGB X 100 HCT RDW%Impedance (from histogram) PlateletX 10 3 /µLImpedance count X cal factor WBC Diff Absolute: X10 3 /µL Percent of WBC : % Light Scatter, flow cytometry

4 M77221

5 CBC Adult Reference Ranges ParameterAdult Reference Range WBC X 10 3 /µL RBC Male: X 10 6 /µL Female: X 10 6 /µL HGB Male: g/dL Female: g/dL HCT Male: 42-52% Female: 36-46% MCV fl MCH28-34 pg MCHC32-36 g/dL or % RDW % PLT X 10 3 /µL MPV fl

6 Linearity (Reportable Range) Instruments are calibrated for each analyte with a range that is clinically relevant. With concentrations above or below the reportable range or Linearity range, the result does not correspond with the calibration curve in linear fashion. Results outside of linearity are NOT acceptable. Linearity ranges vary by instrument. – Example: ParameterCoulter STKSAdvia WBC X 10 3 /µL X 10 3 /µL

7 Advia Linearity Instrument Codes CodeCauseAction Indicated Result exceeds reportable range Dilute 1:2 and rerun. Continue further dilutions until result is within linearity H Result higher than the laboratory set patient high action limit Review Result L Result is lower than the laboratory set patient low action limit Review Result

8 CBC Quality Control Commercial Controls: 3 levels (low, normal, high) Values stored in instrument computer Levey-Jennings graph generated and stored for each parameter Mode to Mode QC: Most automated hematology instruments have a primary and secondary mode of sample aspiration. Controls must be run on BOTH and correlate. – Primary=Automated or Closed – Secondary=Manual or Open Delta Checks When the Laboratory Information System (LIS) and the instrument are interfaced (connected) delta checks are conducted by the LIS on select parameters. – Current values compared to most previous result – Differences greater than the limits set within the LIS are flagged

9 WBC Parameter Interfering substances and Implications TestNameInterfering AgentClinical Implications WBC White Blood Cell Count Unusual RBC abnormalities that resist lysis Nucleated RBCs Fragmented WBCs Unlysed particles greater than 35 fL Very large or aggregated plts Specimens containing fibrin, cell fragments or other debris (esp pediatric/oncology specimens LOW <4.5 X10 3 /µL some medications (such as methotrexate), some autoimmune conditionsautoimmune conditions some severe infections bone marrow failure HIGH: >11.0 X10 3 /µL Infections Inflammation cancer, leukemialeukemia

10 RBC Parameter Interfering substances and Implications TestNameInterfering AgentClinical Implications RBC Red Blood Cell Count Very high WBC count (greater than 99.9) High concentration of very large platelets Agglutinated RBCs, rouleaux will break up when Istoton is added RBCs smaller than 36 fL Specimens containing fibrin, cell fragments or other debris (esp pediatric/oncology specimens LOW: Male: < 4.5 X 10 6 /µL Female: < 4.0 X 10 6 /µL Anemia HIGH: Male: > 5.5 X 10 6 /µL Female: > 5.0 X 10 6 /µL Polycythemia vera, fluid loss due to diarrhea, dehydration, buns diarrhea

11 HGB Parameter Interfering substances and Implications TestNameInterfering AgentClinical Implications HGB Or Hb Hemoglobin Very high WBC count Severe lipemia Heparin Certain unusual RBC abnormalities that resist lysing Anything that increases the turbidity of the sample such as elevated levels of triglycerides High bilirubin LOW: Male: <14 g/dL Female: <12.0 g/dL Anemia HIGH: Male: > 17.4 g/dL Female: >16.0 g/dL Polycythemia vera fluid loss due to diarrhea, dehydration, burnsdiarrhea

12 HCT Parameter Interfering substances and Implications TestNameInterfering AgentClinical Implications HCTHematocrit Known factors that interfere with the parameters used for computation, RBC and MCV LOW: Male: <42% Female: <36% Anemia HIGH: Male: >52% Female: <46% Polycythemia vera fluid loss due to diarrhea, dehydration, burnsdiarrhea

13 MCV Parameter Interfering substances and Implications TestNameInterfering AgentClinical Implications MCV Mean Corpuscular (Cell) Volume Very high WBC count High concentration of very large platelets Agglutinated RBCs RBC fragments that fall below the 36 fL threshold Rigid RBCs LOW: <80 fL Iron deficiency anemia Thalassemia HIGH: >100 fL B12 Folate Deficiency

14 RDW Parameter Interfering substances and Implications TestNameInterfering AgentClinical Implications RDW Red Cell Distribution Width Very high WBC High concentration of very large or clumped platelets RBCs below the 36 fL threshold Two distinct populations of RBCs RBC agglutinates Rigid RBCs HIGH: >14.6% Mixed population of RBCs Immature RBCs tend to be larger

15 Plt Parameter Interfering substances and Implications TestNameInterfering AgentClinical Implications Plt Platelet Count Very small red cells near the upper threshold Cell fragments Clumped platelets Cellular debris near the lower platelet threshold LOW: < 150 X 10 3 /µL Bleeding Wiskott-Aldrich, Bernard-Soulier Systemic lupus erythematosus Pernicious anemia Hypersplenism (spleen takes too many out of circulation) Leukemia Chemotherapy HIGH: >450 X 10 3 /µL Benign idiopathic thrombocytosis Myeloproliferative disorders Polycythemia vera

16 WBC Differential Parameters Clinical Implications in Adults TestNameClinical Implications of LOW % Clinical Implications of HIGH % Neut %Neutrophil % In 100 WBC differential LOW: <40% Chemotherapy Severe infection HIGH: >80% Bacterial infection Inflammatory disease Chronic myelogenous leukemia Lymph %Lymphocyte % LOW: <25% Lupus Later stages of HIV infection.HIV HIGH: >35% Viral infection Chronic or Acute Lymphocytic Leukemia Mono %Monocyte %LOW: <2% Bone Marrow Insufficiency HIGH: >10% Inflammatory disorders Myelomonocytic leukemia Eos %Eosinophil %HIGH: >5% Parasitic infection Allergic reaction Baso %Basophil %HIGH: >1% Allergic reaction to food Chronic inflammation

17 References Harmening., Denise, Clinical Hematology and Fundamentals of Hemostasis, 3 rd edition, pp Turgeon, Mary Louise, Clinical Hematology - Theories and Procedures, 3 rd edition, pp373, Rodak, Bernadette, Diagnostic Hematology, 1 st edition, p Coulter STKS Operating Manual McKenzie, Shirlyn, Clinical Laboratory Hematology, 2 nd edition,pp "Complete Blood Count: The Test." Lab Tests Online: Welcome! American Association for Clinical Chemistry, 18 June Web. 13 Sept "WBC Differential Count: The Test." Lab Tests Online: Welcome! American Association for Clinical Chemistry, 18 June Web. 13 Sept http://www.labtestsonline.org/understanding/analytes/dif ferential/test.html#what>.


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