erythropoietin-independent overproduction of red blood cells (uncontrolled erythrocyte production) • Increased bone marrow sensitivity to growth factors (thrombopoietin & erythropoietin) • Diagnosis is confirmed by JAK2 mutation (present in >95% of patients) and low erythropoietin levels à Erythropoietin receptor • (cytoplasmic tyrosine kinase non-receptor) à replaces a valine with phenylalinine at position 617 à (also with CML)
18 UWorld HEMATOLOGY & ONCOLOGY 4. hepatomegaly ® High RBC turnover 1. Gouty Arthritis ® Kidney stones ® Elevated WBC count Folate Deficiency • Alcoholic • 6-8 lobed neutrophils • Anemia within a few weeks • Increased Homocysteine • NO Methylmalonic Acid (differentiate from Vit. B12) • Poor dietary intake • Differentiate from Vit. B12 deficiency à NO Neuro deficits/Methylmalonic Acid • MCV >100 um • Macrocytosis/ Ovalocytosis • Can be caused by chronic phenytoin therapy (phenytoin,
19 UWorld HEMATOLOGY & ONCOLOGY primidone and phenobarbital) à mild megaloblastic anemia • involves impaired absorption of folic acid in the small intestine. Folic acid supplementation can effectively prevent this condition. 1. 2. Trimethoprim: It inhibits dihydrofolate reductase and in high doses can cause megaloblastic pancytopenia 3. Methotrexate: Also inhibits dihydrofolate reductase. • Folinic acid ( leucovorin } is indicated to reverse the chemotherapeutic anti-folate effect of methotrexate. Pure Red Cell Aplasia (PRCA) • Pallor and fatigue (anemia) • WBC & Platelets normal • Bone marrow precursors appear normal • Normocytic anemia • Low erythrocytes/reticulocytes • Decreased RBC production • Low hemoglobin • A rare form of marrow failure characterized by severe hypoplasia of marrow erythroid elements in the setting of normal granulopoiesis & thrombopoiesis • Inhibition of erythropoietic precursors and progenitors by IgG auto-Ab’s or cytotoxic T-lymphocytes • Can be caused by Thymoma ( Thymic Tumor ), lymphocytic leukemias or Parvovirus (attack & destroy proerythroblasts à blasts) • Chest scan necessary for thymoma • Detect parvo thru anti-B19 IgM Ab’s in serum Intravascular Hemolytic Anemia • Older pt. just underwent a valve replacement • ê serum haptoglobin à ê because of é circ. of Hb (normally haptoglobin helps uptake Hb into RES system) • é serum indirect bilirubin/ LDH • é Hb in serum • Mechanical trauma to erythrocytes as they circulate thru vasculature • Damage can be caused by aortic valve prosthesis or Microangiopathic Hemolytic Anemia (MAHA) • Narrowing of vascular spaces due to fibrin formation cause schistocytes Autoimmune Hemolytic Anemia Pt. with pallor, jaundice, splenomegaly, and laboratory findings (low haptoglobin, elevated LDH, indirect • Due to autoantibodies to (RBCs). • Hemolysis can occur intra- or extravascularly:
20 UWorld HEMATOLOGY & ONCOLOGY (AIHA) hyperbilirubinemia) are consistent w/ hemolytic anemia • Symptoms: ® Fatigue ® Dyspnea ® Splenomegaly ® Anemia with reticulocytosis • Labs: ® Normocytic anemia ® é indirect bilirubin with Jaundice ® é serum LDH ® ê serum Haptoglobin ® é Reticulocytes ® Positive Coombs Test •
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