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MLS Heme lec 8
| Question | Answer |
|---|---|
| 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
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