Red Blood Cell Disorders Flashcards
Anemia
reduction in red cell mass, with consequent decrease in oxygen transport capacity of the blood.
polycythemia
an increase in red cell mass
3 forms of classification for decreased red cell mass
blood loss, decreased RBC survival and decreased BC lifespan
reticulocyte
immautre RBC
intravascular hemolysis characteristics
decreased haptoglobin, hemoblobinemia, hemoglobinuria, hemosiderinuria, hyperbilirubenemia and reticulocytosis
** extravascular hemolysis have similar characteristics, but none of the peeing once and may have an enlarged spleen
hereditary spherocytosis
Extravascular, intrinsic, membrane defective hemolysis
Generally autosomal dominant
Cell membrane defect results in less deformability (smaller, but more rigidity) due to a qualitative/quantitative defect in spectrin which targets them for destruction by the spleen. Mostly in adults w/ variable severity.
Splenectomy increases RBC count (not being destroed in the spleen) but not normal structure; spherocyte production continues and destruction decreases.
Abnormal hemoglobin
ex. sickle cell anemia
extravascular, intrinsic
autosomal codominant
Hb gels upon deoxygenation (low o2 environment) due to a single base pair substitution, causing the cell to take on a sickle conformation (globin chain fucked). Cells are rigid and eliminated by the spleen and can cause ischemia and infarcation. Clinically can present with severe anemia and vaso-occlusive crisis (acute chest syndrome/stroke). 8% of US blacks have the trait but are asymptomatic and resistant to malaria
thalassemia
lack of globin chain, intinsic, extravascular hemolysis
- Diminished/absent alpha/beta globin chains on Hb due to a partial/whole gene deletion, mutations in coding sequence/promoter region or RNA instability. Results in reduced Hb production and anemia. Other globin chains are overproduced, causing membrane instability and premature destruction of RBC precursors. Mild to moderate microcytosis. Common among Mediterraneans, Africans and SE Asians.
- expansion in marrow everywhere (even in jaw) because of ineffective, non-function erythroptoein
Thalassemia forms
Thalassemia major: severe transfusion-dependent anemia and iron overload
minor: mild anemia
glucose 6 phosphate dehydrogenase deficiency
extravascular hemolysis, intrinsic (inherited) metabolis defect
x-linked
RBCs are susceptible to oxidant injury by drugs/toxins; found mostly among blacks. Hb denaturation precipitates it inside the cell and causes it to adhere to RBC membranes, reducing its flexibility, leading to extravascular hemolysis. Asymptomatic in the absence of the oxidant.
** bite cells
erythroblastosis fetalis
extravascular, extrinsic hemolysis
Due to blood group incompatibility between the mother and fetus when the fetus expresses RBC antigens from the father not present in the mother. Initial pregnancy = sensitisizes mother. Subsequent pregnancy = trouble. Rh- mothers are given anti-D 72 hours prior to delivery of an Rh+ fetus. Anti-D binds to Rh+ cells and removes them from maternal circulation before an antibody response is generated.
hemolytic transfusion reaction
intravascular, extrinsic hemolysisTransfusion of incompatible RBCs into a sensitized patient results in binding of antibody (patient) to antigen (transfusion) w/ complement activation. Coag cascade can activate w/ bleeding, renal failure, shock, and death possible. ABO antigens are the most important.
autoimmune hemolysis
extravascular and intravascular , extrinsic defect
- Patient makes antibodies to their own RBCs. Coated RBCs can be lysed (complement system) or removed by reticuloendothelial system. –> find through coombs agglut test
- spherocytes are a hallmark ( in hereditary spherocytosis)
extrinic defects
immune system (Ab attack) or mechanical trauma
intrinsic defect
inherited - hemoglobin production and membrane affected)
Mechanical trauma
ex. cardiac valve prothesis
extrinsic intravascular hemolysisRBCs are disrupted by physical trauma. Ex: DIC where RBCs are lysed as they pass through fibrin clots. Loss of a large portion of membrane results in schistocytes (destroyed membrane cells)
malaria
infection
intravascular, extrinsic hemolysis
Parasites infect RBCs and cause lysis
iron deficiency anemia
Most common cause of anemia (needed for Hg, myoglobin and others). RBCs become smaller and have less Hb - microcytic and hypochromic. Most common in infants (inadaquate intake), adolescents (increased requirements) pregnancy, the elderly and alcoholics. Diagnose via lab tests –> decreased serum iron and ferritin and increased in serum iron-binding capacity)
** can be clinically insidious
Vitamin B12 deficiency
Deficiency can result from decreased intake or malabsorption. Pernicious anemia develops in people who have autoantibodies against intrinsic factor (IF). IF is required for B12 absorption. IF-B12 is absorbed in the distal ileum and then B12 binds transcobalamins which takes it to the liver and bloodstream. B12 deficiency can also cause a demylinating disorder.
** B12 found in animal products
Megoblastic anemia
Result of B12 and folate deficiencies.
Both are used to make thymidine, causing impaired DNA synthesis which causes mitotic delays. Nuclear size increases w/ RNA synthesis and cytoplasmic maturation normal making large RBC precursors, decreased mature RBCs and abnormally large RBCs. Megalobasts accumulate in the marrow, releasing too few RBCs causing anemia. Megaloblasts may lyse or be destroyed by phagocytic cells in the marrow. DNA impairment is systemic and affects other quickly dividing cells.
folate deficiency anemia
Deficiency can result from increased requirements, decreased intake and malabsorption. Body stores are small. Folate is absorbed in the proximal small intestine.
aplastic anemia
Production of all blood cellular elements is decreased. ~1/2 have no known etiologies but viruses, drugs and toxins have been implicated. Could be due to an acquired defect in stem cell production or in suppression of stem cells by T lymphocytes. Issues result from anemia, leukopenia (infection) and thrombocytopenia. Marrow transplants have been successful esp. in patients
pancytopenia
production of all blood (red, platelet and white are decreased
myelophthisic anemia
Normal marrow hematopoetic cells are crowded by tumors or fibrosis.
