L2 - Pathology Of RBCs Flashcards
What is the MCV?
Mean corpuscular volume
Hct/RBC
What is the MCH?
Mean corpuscular hemoglobin
Hgb/RBC
What is the MCHC?
Mean corpuscular hemoglobin concentration
Hgb/Hct
What does a low MCV indicate?
Microcytic anemia
What does a high MCV indicate?
Macrocytic anemia
What does a low MCH indicate?
Hypochromic anemia
How do reticulocytes appear on a peripheral smear?
Polychromatic with a purple grey tinge in larger cells
What is the RDW?
Red cell distribution width
Measure of variability in size of circulation erythrocytes
Increased RDW can be seen in many conditions including what?
Iron deficiency anemia
What are normal adult hemoglobins?
Hemoglobin A (97%) Hemoglobin A2 (2-3%) Hemoglobin F (<1%)
If you are heterozygous for S you have what?
Sickle cell trait
1 in 12 persons of African descent
If you are homozygous for S you have what?
Sickle cell disease
Populations with high incidence of HbS may have other variant hemoglobins such as?
HbC
Beta thalassemia
What are the effects of chronic hemolysis?
Jaundice and gallstones
Anemia
What are the effects of vascular occlusion?
Stroke, retinopathy, acute respiratory distress, acute chest syndrome, cor pulmonale, hepatic sequestration, hematuria and polyuria, autosplenectomy and infections, aseptic bone necrosis and osteomyelitis, placental failure in pregnancy, leg ulcers
What are the effects of absence of all alpha globin genes?
Anemia and tissue hypoxia
Massively enlarged placenta leading to maternal complications, heart failure leading to large heart, pericardial effusion, edema, ascites and pleural effusion, congenital anomalies, large liver and spleen
What is a direct antiglobulin test (DAT) (Coombs test)?
Detects the presence of Ab bound to the red cell surface
- Autoimmune hemolytic anemia
- Hemolytic disease of newborn
- Transfusion reactions
What is the indirect antiglobulin test (IAT)?
Detects abs in the plasma
- Ab screen in pretransfusion testing
- Screening in pregnancy for abs that may cause hemolytic disease of newborn
What is warm hemolytic anemia?
IgG (most typical Ig subtype) binds stably at 37C
These opsonized cells are phagocytosed in the spleen or gradually lose membranes
Autoimmune or drugs
What is cold hemolytic anemia?
IgM
Stronger affinity at low temps
More likely to manifest in nose and fingertips (Raynaud)
IgM leads to C3b deposition and the liver, spleen and bone marrow remove the cells
What labs should be performed to evaluate vessel wall abnormalities?
Labs dont really help
Which labs should be performed to evaluate reduced platelet numbers?
CBC for platelet count
Which labs should be performed to evaluate defective platelet function?
Platelet function test, morphology
Which test should be performed to evaluate clotting factor abnormalities?
PT and PTT
What is the presentation of platelet disorders?
Superficial mucosal bleeding Petechiae Small superficial bruises Rare for hemarthroses Bleeding after minor cutes
What is the presentation for coagulation disorders?
Deep soft tissue bleeding Minimal petechiae Large deep bruises Common hemarthroses Delayed bleeding after cuts
Factor deficiencies or dysfunction will result in what?
Prolongation of aPTT and/or PT
Describe SC disease
Milder than sickle cell disease
Hb C can crystallize but doesn’t polymerize (although dehydration can result in polymerization)
Same general complications and risks but less severe
More likely to see Target cells than true sickle cells (poikilocytes)
What are the stages of iron deficiency?
- Reduced ferritin
- Iron deficiency
- Iron deficiency anemia
Described the reduced ferritin stage of iron deficiency
Decreased serum ferritin <50-70
Decreased bone marrow iron
Hb normal
Sx start
Describe the stage of iron deficiency
Decreased serum ferritin <30
Absent bone marrow iron
Hb low/normal range
Sx accelerate
Describe the factor VIII-vWF complex
vWF carries Factor VIII to a platelet so that it can contribute to the clotting cascade
vWF then goes and contributes to the repair of the endothelial defect
