Red Blood Cell Disorders

Question 1

Anemia

Answer 1

reduction in red cell mass, with consequent decrease in oxygen transport capacity of the blood.

Question 2

polycythemia

Answer 2

an increase in red cell mass

Question 3

3 forms of classification for decreased red cell mass

Answer 3

blood loss, decreased RBC survival and decreased BC lifespan

Question 4

reticulocyte

Answer 4

immautre RBC

Question 5

intravascular hemolysis characteristics

Answer 5

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

Question 6

hereditary spherocytosis

Answer 6

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.

Question 7

Abnormal hemoglobin

Answer 7

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

Question 8

thalassemia

Answer 8

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

Question 9

Thalassemia forms

Answer 9

Thalassemia major: severe transfusion-dependent anemia and iron overload
minor: mild anemia

Question 10

glucose 6 phosphate dehydrogenase deficiency

Answer 10

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

Question 11

erythroblastosis fetalis

Answer 11

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.

Question 12

hemolytic transfusion reaction

Answer 12

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.

Question 13

autoimmune hemolysis

Answer 13

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)

Question 14

extrinic defects

Answer 14

immune system (Ab attack) or mechanical trauma

Question 15

intrinsic defect

Answer 15

inherited - hemoglobin production and membrane affected)

Question 16

Mechanical trauma

Answer 16

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)

Question 17

malaria

Answer 17

infection
intravascular, extrinsic hemolysis
Parasites infect RBCs and cause lysis

Question 18

iron deficiency anemia

Answer 18

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

Question 19

Vitamin B12 deficiency

Answer 19

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

Question 20

Megoblastic anemia

Answer 20

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.

Question 21

folate deficiency anemia

Answer 21

Deficiency can result from increased requirements, decreased intake and malabsorption. Body stores are small. Folate is absorbed in the proximal small intestine.

Question 22

aplastic anemia

Answer 22

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

Question 23

pancytopenia

Answer 23

production of all blood (red, platelet and white are decreased

Question 24

myelophthisic anemia

Answer 24

Normal marrow hematopoetic cells are crowded by tumors or fibrosis.

Question 25

polysythemia

Answer 25

increase in red cell mass
relative - after dehydration, vomit or shitting
absolute - primary or secondary

Question 26

absolute primary polysythemia

Answer 26

Normal/low levels of erythropoietin caused by non-regulated proliferation of RBCs and myeloid cells; stem cell disorder. Tx is removal of RBCs via phlebotomy.
not common
polycythena vera forms (accum of rbc and myeolid cells)

Question 27

absolute secondary polysythemia

Answer 27

Increase in erythropoietin (cyanotic heart disease, pulmonary disease, living at high altitude, abnormal hemoglobin, erythropoietin-producing tumors)