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Hematology
Blood neoplasms, disorders of clotting, sepsis etc.
28
Medical
Graduate
04/24/2010

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Cards

Term
Thrombocytopenia and microangiopathic hemolytic anemia (elevated indirect bilirubin+reduced serum haptoglobin) should include what conditions in the differential?
Definition
Thrombotic thrombocytopenic purpura and hemolytic-uremic syndrome (TTP-HUS)
Term
Widespread hyaline thrombi formation, made up of platelet aggregates, which lodge in the microvasculature is the underlying cause of what two conditions?
Definition
TTP-HUS
Term
What is the etiology of TTP?
Definition
Absence, acquired or congenital, of ADAMTS13, a metalloprotease unrelated to those involved in extracellular matrix degradation. ADAMTS13 is responsible for degrading vonWillebrand Factor. When deficient, too much vWF is present on endothelial cells, leading to platelet aggregation and formation of thrombi
Term
This treatment is life-saving for TTP
Definition
Plasma exchange, which replaces the deficient ADAMTS13 metalloprotease
Term
Since MAHA is non-immune mediated hemolysis, what causes RBC destruction?
Definition
Shear stresses imposed by obstructive thrombi in the microvasculature damage RBCs as they pass through capillaries
Term
What is the most common cause of HUS?
Definition
EHEC, especially O157:H7, produces a shiga-toxin that damages endothelial cells resulting in platelet aggregation, complement deficiences and drug reactions can also cause HUS
Term
What is the primary distinction between DIC and TTP-HUS?
Definition
DIC requires an inappropriate activation of the clotting cascade to occur, while TTP-HUS results from inappropriate platelet aggregation
Term
T or F: synthesis of hemoglobin begins in the proerythroblasts and continues even into the reticulocyte stage of the RBCs
Definition
True
Term
Outline the steps of hemoglobin synthesis
Definition
SuccinylCoA (from Krebs)+glycine->pyrrole(x4)->protoporphyrin IX+iron->heme+globin->hemoglobin chain (x4)->hemoglobin molecule
Term
T or F: Hemoglobin B is the most common form of human hemoglobin
Definition
False, hemoglobin A which has 2 alpha and 2 beta chains
Term
The total quantity of iron in the body is: a) 4-5 grams b) 2-3 grams c)7-8 grams or d) 10-12 grams
Definition
a, 4-5 grams, 65% in hemoglobin, 4% in myoglobin, 1% in heme components of CYP family proteins, .1% in serum bound to transferrin and 15-30% in storage, mainly in the reticuloendothelial system and liver parenchymal cells
Term
What is the dominant storage form of iron
Definition
In ferritin
Term
T or F: Iron is absorbed in the distal ileum 
Definition
F, absorbed in the duodenum by the DMT transporter on the brush border, where it is taken up into enterocytes
Term
Which enzyme facilitates the rate limiting step in heme production?
Definition
ALA synthase
Term
Where does the rate limiting step of heme synthesis take place in the cell?
Definition
Mitochondria
Term
T or F: After ALA leaves the mitochondrion it goes to the cytosol and condenses with another ALA to form uroporphyrinogen
Definition
False, forms porphobilinogen (PBG)
Term
Which intermediate in heme synthesis is water soluble and can turn up in urine in case of excess?
Definition
Uroporphyrinogen
Term
Which intermediate in heme synthesis is excreted in feces if in excess, and which steps does it precede/succeed?
Definition
coproporphyrinogen, comes before synthesis of protoporphyrinogen IX and after formation of uroporphyrinogen
Term
T or F: After protoporphyrinogen IX is reduced to protoporphyrin IX, ferrous iron is inserted by ferrochelatase
Definition
False, it is oxidized to protoporphyrin IX but the rest is correct
Term
T or F: as the rate limiting step in heme synthesis, ALA synthase is the body's regulatory target in heme synthesis
Definition
True, when more is needed it is up regulated and vice versa
Term
How are the two ALA synthase genes regulated?
Definition
One is expressed in all cells and responds to heme concentrations, the other is only in proerythroblasts and responds to EPO
Term
Name a common cause of acquired porphyria that works by inhibiting ALA dehydratase and ferrochelatase
Definition
Lead poisoning
Term
What is the protein responsible for moving ferrous iron into the bloodstream from enterocytes?
Definition
Ferroportin
Term
T or F: The highest sensitivity transferrin receptors are found in the liver and bone marrow
Definition

True, remember transferrin is the protein that transports iron in the blood

 

Term
What storage form of iron is utilized only when ferritin is unavailable?
Definition
Hemosiderin, extermely insoluble and can be observed in cells indicating iron overload
Term
T or F: Transferrin delivers iron directly to mitochondria for heme synthesis to take place
Definition
True
Term
What is the most common cause of iron deficiency anemia in men?
Definition
Blood loss from a gastrointestinal bleed
Term
What is the name of the inhibition target in erythroid precursor cells for low hemoglobin?
Definition
Heme regulated translational inhibitor
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