Red Blood Cell and Bleeding Disorders Flashcards
(38 cards)
Characterized by defective red cell membrane proteins spectrin and ankyrin; on PBS, red cells are spherical which lack central pallor, and they show increased osmotic fragility when placed in hypotonic salt solutions; anemia with characteristically increased MCHC.
Hereditary spherocytosis (Intrinsic; extravascular)
X-linked disorder in which red cells are unusually susceptible to damage cause by oxidants. (Drugs that produce oxidants include antimalarials, sulfonamides, nitrofurantoin, phenacetin, and vitamin K derivatives); Heinz bodies (derived from hemoglobin) seen on PBS of splenectomized patients; Bite cells seen on PBS of patients with intact spleen function.
Glucose-6-phosphate dehydrogenase deficiency (G6PD deficiency) (Intrinsic; extravascular and intravascular)
This results from substitution of valine for glutamic acid at the 6th position of the b-chain, producing HbS; bizarre, elongated, spindled or boat-shaped cells on PBS (evident on low oxygen tension states); clinically, prominent cheekbones and changes in skull resembling a crew-cut skull x-ray, due to bone marrow expansion; also with painful vaso-occlusive crisis; spleen may be enlarged, but in chronic cases may be small and fibrosed (autosplenectomy), rendering them susceptible to infections with encapsulated bacteria; treatment is Hydroxyurea that increases HbF.
Sickle cell anemia (Intrinsic; extravascular)
Microcytic, hypochromic anemias characterized by deficiency of either a- or b-globin chains (memory device: the name is what it lacks).
Thalassemia (Intrinsic; extravascular)
Condition caused by deletion of 1 a- globin gene.
Silent carrier
Condition caused by deletion of 2 a- globin genes; symptomatic at birth because of deficiency in HbF.
a-Thalassemia
Disease caused by deletion of 3 a-genes.
Hemoglobin H disease
Condition caused by deletion of all four a-globin genes.
Hydrops fetalis
In b-Thalassemia, an individual who inherits one abnormal allele (out of 2) has this asymptomatic to mildly symptomatic condition; Red cells with a central, dark-red puddle due to collection of hemoglobin (target cells) on PBS.
b-Thalassemia minor
Individuals with b-Thalassemia who inherit two abnormal alleles, with severe anemia requiring regular blood transfusions; usually symptomatic at around six months of age because HbF synthesis ceases at this time; marked hypochromia, poikilocytosis (variation in cell size) and anisocytosis (variation in cell shape) with normoblasts (signifying erythropoietic drive).
b-Thalassemia major (Cooley anemia)
A mutation in the gene pigA causes this disease; there is deficiency of PIG (phosphatidylinositol glycan) that anchors CD55 and CD59 to the red cell surface; without such, red cells become susceptible to complement-mediated lysis.
Paroxysmal nocturnal hemoglobinuria (Intrinsic; intravascular)
Anemia caused by low-affinity IgM which bind to red cell membranes only at temp <30 degC, commonly experienced by distal parts of the body; associated with Mycoplasma pneumoniae, and EBV infections.
Cold antibody immune-hemolytic anemia (Extrinsic; intravascular)
Hemolysis caused by IgG or IgA antibodies that are active at 37 deg C, which results in opsonization of red cells by the autoantibodies.
Warm antibody immune-hemolytic anemia (Extrinsic; intravascular)
Anemia observed in a variety of pathologic states, in which small vessels become particularly obstructed (e.g. DIC, malignant HTN, SLE, etc.); schistocytes, Burr cells, helmet cells, triangle cells are seen in this condition.
Microangiopathic hemolytic anemia (Extrinsic; intravascular)
Most common cause of anemia in both developing and developed countries; microcytic, hypochromic with low ferritin, low serum iron levels low transferrin saturation, and increased TIBC.
Iron deficiency anemia
Most common cause of anemia in hospitalized patients; anemia characterized by high levels of hepcidin, responsible for blocking the transfer of iron to erythroid precursors, hence causing anemia; normocytic, normochromic but can be microcytic, hypochromic; increased ferritin, low serum iron levels, low transferrin saturation, and decreased TIBC.
Anemia of chronic disease
Anemia characterized by hypercellular marrow as a result of increased number of megaloblasts, which are large cells that have delicate, finely reticulated nuclear chromatin and abundant basophilic cytoplasm; can be caused by Folate (without neurologic symptoms) or Cobalamin (with neurologic symptoms) deficiency; PBS findings include: hypersegmented neutrophils, large, egg-shaped macro-ovalocytes.
Megaloblastic anemia
Bone marrow is markedly hypocellular, with >90% of the intertrabecular space being occupied by fat; normocytic, normochromic; most commonly caused by chemicals (Benzene) and drugs (Chloramphenicol).
Aplastic anemia
Selective suppression of marrow erythroid precursors; can be autoimmune or infectious (Parvovirus) in etiology; presents with normocytic, normochromic anemia with virtuallyt absent eryhtroblasts in bone marrow, and normal granulo- and thrombopoietic elements; paraneoplastic syndrome of thymoma.
Pure red cell aplasia (PRCA)
Anemia caused by replacement of the bone marrow by in infiltrative processes such as metastatic carcinoma and granulomatous disease; leads to the appearance of early erythroid and granulocytic precursors (leukoerythroblastosis) and teardrop-shaped red cells (dacrocytes) in the peripheral blood.
Myelophthisic anemia
Denotes an increase in red cells per unit volume of peripheral blood, usually in association with an increase in hemoglobin concentration; maybe relative (hemoconcentration) or absolute; absolute may be primary (polycythemia vera) or secondary (increased erythropoietin, lung disease, high altitude, endurance athletes or erythropoietin-secreting tumors).
Polycythemia
Caused by a systemic activation of coagulation pathways, leading to formation of thrombi throughout the microcirculation, and subsequent bleeding due to consumption of coagulation factors; laboratory findings include: thrombocytopenia, increased bleeding time and prolonged PT and PTT.
Disseminated intravascular coagulation (DIC)
Caused by antiplatelet antibodies directed against glycoproteins IIb-IIIa, Ib-IX (usually IgG); laboratory findings include: decreased platelet count, prolonged bleeding time, and normal PT and PTT.
Immune thrombocytopenia/Immune thrombocytopenic purpura (ITP)
Form of ITP usually affecting adults and females more than males; associated with SLE, HIV, B-cell neoplasms (CLL); glucocorticoids are indicated; other tretament modalities include, splenectomy, rituximab (anti CD20) in B-cell neoplasms, and TPO-mimetic (Romiplostim).
Chronic ITP
