Hem & Onc - Pathology (Normocytic anemia) Flashcards
Pg. 384-387 in First Aid 2014 or Pg. 354-357 in Fist Aid 2013 Sections include: -Normocytic, normochromic anemia -Nonhemolytic, normocytic anemia -Intrinsic hemolytic normocytic anemia -Extrinsic hemolytic normocytic anemia
What defines normocytic anemia?
Anemia with blood cells of MCV of 80-100 fL
What are the divisions of normocytic, normochromic anemias?
Hemolytic and nonhemolytic
What are the divisions of hemolytic, normocytic anemias? What is the basis for this classification?
(1) Intrinsic vs. Extrinsic (2) Intravascular vs. Extravascular; According to cause of hemolysis (i.e., whether intrinsic or extrinsic to the RBC) & by location (i.e., intravascular vs. extrascular)
What are lab findings that characterize intravascular hemolysis?
(1) DECREASED HAPTOGLOBIN (2) Increased LDH (3) Blood smear - schistocytes & increased reticulocytes (4) Urobilinogen in urine (e.g., paroxysmal nocturnal hemoglobinuria, mechanical destruction [aortic stenosis, prosthetic valve], microangiopathic hemolytic anemias)
What happens in extravascular hemolysis? What are physical and lab findings that characterize this?
Macrophages in spleen clear RBCs; (1) Increased LDH (2) Increased LDH plus (3) INCREASED UCB (i.e., unconjugated bilirubin), which causes JAUNDICE (e.g., hereditary spherocytosis)
What are lab values that help you distinguish between intravascular and extravascular hemolysis?
Intravascular = decreased haptoglobin (& possibly Hb in urine); Extravascular = increased UCB (leading to jaundice)
What are examples of nonhemolytic, normocytic anemia?
(1) Anemia of chronic disease (ACD) (2) Aplastic anemia (3) Chronic kidney disease
By what process does anemia of chronic disease occur?
Inflammation –> Increased hepcidin (released by liver, binds ferroportin on intestinal mucosal cells and macrophages thus inhibiting iron transport) –> Decreased release of iron from macrophages
What are the lab findings (i.e., iron studies) of ACD?
(1) Decreased iron (2) Decreased TIBC (3) Increased ferritin
What is unique about ACD in terms of its classification?
Typically starts as a nonhemolytic, normocytic anemia but can become a microcytic, hypochromic anemia
In general, what event(s) cause(s) aplastic anemia? More specifically, what are examples of things that cause this event to occur, and consequently lead to aplastic anemia?
Caused by failure or destruction of myeloid stem cells; (1) Radiation and drugs (benzene, chloramphenicol, alkylating agents, antimetabolites) (2) Viral agents (parvovirus B19, EBV, HIV, HCV) (3) Fanconii’s anemia (DNA repair defect) (4) Idiopathic (immune mediated, primary stem cell defect) - may follow acute hepatitis
What blood cell findings characterize aplastic anemia? What about bone marrow findings?
Pancytopenia characterized by severe anemia, leukopenia, & thrombocytopenia; Normal cell morphology but hypocellular bone marrow with fatty infiltration (dry bone marrow tap)
What are the symptoms of aplastic anemia?
(1) Fatigue (2) Malaise (3) Pallor (4) Purpura (5) Mucosal bleeding (6) Petechiae (7) Infection
What are the treatment options for aplastic anemia?
(1) Withdrawal of offending agent (2) Immunosuppressive regimen (antithymocyte globulin, cyclosporin) (3) Allogeneic bone marrow transplantation (4) RBC and platelet transfusion (5) G-CSF (6) GM-CSF
How does chronic kidney disease lead to nonhemolytic, normocytic anemia?
Decreased erythropoietin (EPO) –> Decreased hematopoiesis
What are examples of intrinsic hemolytic normocytic anemia? Which of these are extravascular versus intravascular?
(1) Hereditary spherocytosis = E (2) GP6D deficiency = I or E (3) Pyruvate kinase deficiency = E (4) HbC defect = E (5) Paroxysmal nocturnal hemoglobinuria = I (6) Sickle cell anemia = E
What is the defect in hereditary spherocytosis?
Defect in proteins interacting with RBC membrane skeleton & plasma membrane (e.g., ankyrin, band 3, protein 4.2, spectrin)
Describe and explain the morphology of RBCs seen in hereditary spherocytosis.
Less membrane causes small and round RBCs with no central pallor (increased MCHC, increased red cell distribution width)
How does hereditary spherocytosis often present?
(1) Splenomegaly (2) Aplastic crisis (parvovirus B19 infection)
What lab findings characterize hereditary spherocytosis?
Positive osmotic fragility test; Normal to decreased MCV with abundance of cells; masks microcytia
What is the treatment for hereditary spherocytosis, and why?
Splenectomy; Because premature removal of RBCs (spherocytes) by spleen due to augmented RBC morphology (Recall specifics: less membrane causes small and round RBCs with no central pallor [increased MCHC, increased red cell distribution width] –> premature removal of RBCs by spleen)
What is the hereditary nature of G6PD deficiency?
X-linked
What effect does a defect in G6PD have?
Defect in GP6D –> Decrease Glutathione –> Increase RBC susecptibility to oxidant stress
What are 4 causes of oxidant stress? With what hematologic disorder is oxidant stress associated?
(1) Sulfa drugs (2) Infections (3) Fava Beans (4) Antimalarials; G6PD deficiency
In G6PD deficiency, where are RBCs primarily destroyed?
Extravascular (but also minimal intravascular)
What are signs/symptoms associated with G6PD deficiency? What do lab results classically show?
Back pain, hemoglobinuria a few days after oxidant stress; Blood smear shows RBCs with Heinz bodies and bite cells; Think: “STRESS makes me eat BITES of FAVA BEANS with HEINZ ketchup.”
What is the hereditary nature of pyruvate kinase deficiency?
Autosomal recessive
What effect does a defect in pyruvate kinase have?
Decreased ATP –> rigid RBCs