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MLS Heme lec 8

QuestionAnswer
4 common lab tests ESR-inflammation Hgb-anemia Hct-anemia Indices-cell morphology
What does ESR stand for Erythrocyte sedimentation rate
ESR test is Simple, non-specific screening test for inflammation
ESR test steps 1. Anticoagulated blood is allowed to stand undisturbed for 1 hour 2. RBCs settle slowly,due to small mass, to bottom of the tube
Rouleaux stacking of red blood cells
Rouleaux indicates certain diseases increase rouleaux, increasing RBC mass and causing increased fall-out rate
Definition ESR distance in mm that RBCs will fall in 1 hr in a vertical tube of defined length
Fall-out proportions Directly: red cell mass Inversely: plasma viscosity
Zeta cloud of negative charges found on cell membrane
What weakens the zeta potential Fibrinogen and other proteins by attracting positive ions close to the cell
Fibrinogen Acute phase reactant
Weakened zeta potential allows Rouleaux and fall-out
Increased RBC fall-out indicates Increased fibrinogen In vivo rouleaux of cells Multiple myeloma increases immunoglobulin
Decreased RBC fall-out Polycythemia Sickle cells Spherocytes
Normal RBC fall-out Male: 0-20 mm/hr Female & Children: 0-15 mm/hr value related to red cell count
ESR Methods Wintrobe Wetergren Automated
Westergren method considered the universal reference method
Automated method Shorter times, approximately 20 min
Technical factors affecting ESR results Vertical slant Temperature Bubbles Abnormal shapes Won't rouleax
ESR Values Cannot be "decreased" since zero is normal
Hemoglobin is the best measure of anemia
Increased inflammatory conditions Infections, especially bacterial Auto-immune diseases Neoplasms
Hemoglobin measurement all but sulfhemoglobin with cyanmethemoglobin as a reference
Sulfhemoglobin can occur from antibiotics or pesticides
Methemoglobin reacts with cyanide to create Cyanmethemoglobin (HiCN)
Based on Beer's Law concentration is Absorbance of HiCN is proportional to Hgb
Transmission absorbance measured spectrophotometrically at 540nm
Hemoglobin Reference Range Male: 12-16 g/dL Female: 14-18 g/dL Newborn: 22 g/dL Children: 11-14 g/dL
Hct, PCV Hematocrit Packed cell volume
Hct expressed as Percentage of whole volume RBC
Hct test Manual method uses capillary tubes. Automated is % of whole blood after centrifugation
Manual Hct test Capillary tube is filled with blood and centrifuged at 8000g (11,000-15,000 RPM) for five minutes. Omit buffy coat. Use special device to read % of RBC
Automated Hct Not directly measured when automated instruments are used. Corrective calculation must be done
Indirect Hct calculation RBC x MCV/10
Automated Hct disadvantage In-vivo agglutination occurs, will affect Hct. RBC and MCV will be erroneous
Automated Hct advantage No trapped plasma
When is manual Hct performed Suspect spurious automated results or cannot get a tube of blood
Rule of 3 Hct should be 3x Hgb, +/- 3%
Reference Range for Hct Male: 42-52% Female: 37-47% Newborn is higher
RBC indices Numerically describes cell morphology
MCV mean cell volume Indicates size or volume of cell. Higher number, larger cell.
What can cause a falsely elevated MCV Agglutination
Automated instruments measure MCV by Size of pulse and derived from histogram
MCV calculation (Hct/RBC) x 10=fL
MCV reference range 80-100fL
MCV Determines normocytes, macrocytes, and microcytes
MCH mean cell hemoglobin average weight of hemoglobin, usually 1/3 MCV
MCH calculation (Hgb/RBC) x 10= pg
MCH reference range 28-32pg
MCH & MCHC values are always calculated
MCH & MCHC value corresponds to hypochromasia (decreased Hgb) or hyperchromasia (increased Hgb)
What can alter the value of the MCH lipemic specimen or cold agglutinin
MCHC mean cell Hgb concentration Average Hgb concentration of all red cells in sample, usually corresponds to MCH
MCHC Calculation (Hgb/Hct) x 100 = value in %
MCHC Reference Range 30-36%
Hypochromasia decreased cellular hemoglobin concentration
Hyperchromasia to much hemoglobin for size of the cell, observed in spherocytes or artifact
RBC Morphology: normocytic, normochromic Conditions: normal, anemias, most hemoglobinopathies
RBC Morphology: Moderate anisocytosis, increased RDW:more variation in size Conditions: sideroblastic anemia, transfusion, or treated anemia
RBC Morphology:Slight macrocytes, increased MCH ,right shift MCHC, increased MCV usually Conditions: Liver disease
RBC Morphology: Moderate anisocytosis & moderate macrocytes, all markers elevated Cnditions: Megaloblastic anemia (B12 & folate), reticulocytes & myelodysplasia
RBC Morphology: Moderate anisocytosis; moderate hypochromasia, all markers low Conditions: Thalssemia
RBC Conditions: Moderate anisocytosis, slight microcytosis, slight hypochromasia. MCV,MCH,RDW increased Conditions: Iron deficiency, sideroblastic anemia, lead poisoning
RBC Morphology: Moderate anisocytosis, moderate spherocytes. MCH, MCHC increased & MCV wider Conditions: Hereditary spherocytosis & autoimmune hemolytic anemia (AIHA)
Created by: mlrlemons