Hematopathology Flashcards
What three pathophysiological processes can lead to anemia?
Blood loss
Impaired RBC production
Increased RBC consumption or destruction
What are the two broad categories of RBC disorders?
Erythrocytosis - increased RBC mass
Anemia - decreased RBC mass resulting in decreased capacity to deliver oxygen
What six ways does the body use to compensate for tissue hypoxia in the face of anemia?
Increase RBC production by increasing epo
Increasing efficiency of oxygen delivery by increasing 2,3 DPG
shunt blood to vital areas –> pallor
Increase cardiac function –> increased hr
Increase or restore blood volume
Increase pulmonary function –> increased rr
How long do RBCs normally last in circulation?
100-120 days
How can CBC be used to test for anemia?
Includes RBC count, RBC indices, WBC count and platelet count
Anemia confirmed by low hb concentration and/or low hematocrit
Once anemia is diagnosed, what is the next broad categories they can be grouped into?
Microcytic
Normalcytic
Macrocytic
Based on mean corpuscular volume
After sorting according to mcv, what sorting step comes next for anemia?
Mean corpuscular hemoglobin concentration (MCHC) separates into hyperchromic, normochromic, or hypochromic
Central pallor should be about 1/3 diameter of cell
After mcv and mhch parameters have been established, what other measures can be used to categorize anemias?
RBC distribution width (RDW)
RBC count
Reticulocyte count
What is the RDW?
Coefficient of variation of RBC volume
Higher RDW means more variation in size
Can categorize anisocytotic vs. non-anisocytotic
Which anemia is associated with a high RBC count and which with low?
Thalassemia
Iron deficiency
Under normal conditions what should the reticulocyte percentage be?
0.5-1.5%
If there is normal RBC proliferation and maturation, how long after a blood loss should an increase in reticulocytes be seen in the peripheral blood?
2-3 days
Why must the reticulocytes count be adjusted using the corrected reticulocyte count?
Because if an anemia is due to RBC depletion, the percentage of reticulocytes will be proportionally higher
How can reticulocytes be seen in the peripheral blood?
Special stain can stain for basophilic matrix of rRNA still present
How many days do reticulocytes spend in the bone marrow and then the periphery before being fully mature?
3 days
1 day
Why is the reticulocyte count further modified to the reticulocyte production index?
Because in anemia, they are released into the periphery at an earlier stage of maturation and thus spend less time in the bone marrow and more time there
How are the results of the RPI used?
Not anemic - RPI should be 1-2%
Anemic - RPI3 means adequate bone marrow response, suggests anemia secondary to RBC destruction, etc.
How does anemia from acute blood loss happen?
CBC will not recognize anemia until intravascular volume replenished either by transmigration of tissue fluid or therapy
After compensatory shift can identify cytopenias due to dilution
Normocytic and normochromic
How does anemia in chronic blood loss happen?
Initial stages - bone marrow increases RBC production and compensates –> CBC might be normal but reticulocyte count up
Over time, iron will become depleted –> type of anemia of iron deficiency
What is important about iron deficiency in the elderly?
Should be regarded as right sided colon cancer until proven otherwise as this is common etiology of chronic blood loss in that demographic
What type of anemia is that due to proliferation defects?
Normocytic, normochromic
What is aplastic anemia?
Stem cell defects lead to failure of production of hematopoietic lineages
Bone marrow becomes hypo cellular and peripheral blood becomes pancytopenic
Has adequate epo
What is myelophthisic anemia?
Bone marrow is replaced by nonhematopoietic tissue
Body shifts production of blood cells to liver and spleen - not normal regulatory environment –> release of immature cells
Teardrop cells (dacrocytes) in peripheral blood
Only proliferation anemia with that may have increased reticulocyte count
What are the basic feature of maturation defect anemias?
Bone marrow hyper cellular with increased RBC precursors
Peripheral blood has too few mature RBC
Also called ineffective erythropoiesis
What kind of anemia is iron deficiency anemia?
Microcytic, hypochromic
What happens during the development of iron deficient anemia?
Body mobilizes iron stores then
Plasma ferritin decreases as storage iron decreases, plasma iron falls, plasma transferrin rises - can be seen before cell changes
Anemia develops once stores exhausted
Early normochromic and normocytic, then microcytic, then hypochromic
What other changes are seen with cells in iron deficiency anemia?
Anisocytosis
Poikilocytosis
Low RBC count
Low reticulocyte count
What is the gold standard for diagnosis of iron deficiency?
Prussian blue reaction on bone marrow aspirate
Both iron stores in histiocytes and sideroblastic iron in erythrocytes will be absent
What is the cause of megaloblastic anemia?
Folate or cobalamin deficiency
Cofactors needed for dTMP which is needed for DNA
Impaired nuclear synthesis with intact cytoplasmic synthesis - opposite of iron deficiency anemia
What are the features of megaloblastic anemia?
Macrocytosis (MCV>100)
High RDW
Low reticulocyte count
Maybe leukocytopenia or thrombocytopenia
Nucleated RBCs, basophilic stippling, RBC fragments, teardrop cells and lack of polychromasia in periphery
Hyper segmented neutrophils
Serum lactate dehydrogenase and bilirubin increased
What five additional tests should be ordered in megaloblastic anemia after initial findings?
Serum cobalamin
Serum folate
RBC folate
Serum methylmalonic acid - only increases with cobalamin deficiency
Serum homocysteine - accumulates with both cobalamin and folate deficiency
What is the probable cause of b12 deficiency as opposed to folate?
Lots of b12 stores in body - probs an absorption problem
Folate usually due to decreased intake
What are changes on bone marrow exam associated with megaloblastic anemia?
Hypercellularity
Shift toward immaturity = left shift
Megaloblastic features in precursor cells
What are some features seen in myelodysplastic syndromes but not megaloblastic anemia?
hyposegmented neutrophils
Hypo granulated granulocytes
What are features seen in megaloblastic anemia but not myelodysplastic syndromes?
Hypersegmented neutrophils
Giant metamyelocytes
Giant band neutrophils
Abnormal ancillary studies
What is anemia of chronic disease?
Associated with inflammatory states like infection or malignancy
Related to release of inflammatory cytokines that act to decrease iron absorption, induce macrophage sequestration of iron, and decrease epo
What do lab tests of anemia of chronic disease show?
Decreased serum iron
Increased serum ferritin
Decreased iron binding capacity
What does bone marrow exam of anemia of chronic disease show?
Normal numbers of RBC precursors
Increased iron stores with absent sideroblastic iron
Hb levels rarely fall below 9
80% are normocytic and normochromic, ret are microcytic and hypochromic
What are lab findings in hemolytic anemia?
Signs of bone marrow compensation/increased RBC production
Signs of increased RBC destruction (increased lactate dehydrogenase, increased serum unconjugated bilirubin, increased urobilinogen, decreased haptoglobin)
What kinds of intrinsic defects can cause hemolytic anemia?
Abnormalities in hemoglobin, membrane or enzymatic machinery
What is paroxysmal nocturnal hemoglobinuria (PNH)?
Defect in PIG-A gene leads to dysfunctional GPI anchors on RBC membranes
Normally anchor cd55 and cd59 which regulate complement lysis
What is sickle cell disease?
Valine sub for glutamic acid in beta globin
Manifestations of vaso-occlusive episodes include pain crisis, acute chest syndrome, renal dysfunction, priapism, and retinal pathology
Baseline hb between 6-10
What kind of anemia is that which results from sickle cell?
Normocytic and normochromic
Marked anisopoikilocytosis
What do peripheral blood smears of sickle cell anemia show?
Sickle cells and variants - blister cells, spherocytes, evidence of hyposplenism (uncleared RBCs, target cells, Howell-jolly bodies, and pappenheimer bodies)
Might have some fetal hemoglobin
How does thalassemia lead to hemolysis?
Defect in synthesis of either alpha or beta chain increases synthesis of the other - then excess precipitates within RBC
What kind of anemia is thalassemia?
Microcytic and hypochromic
What kinds of mutations are usually in alpha thalassemia and what kind in beta?
Gene deletions - one gene deletion typically silent
Point mutations in regulatory regions
What is seen in the peripheral blood smear of less severe thalassemias?
Small RBCs with mild anisocytosis and poikilocytosis