Deck XVIII

Question 1

What antineoplastic drug is an adenosine analog and reaches high intracellular concentrations due to resistance to adenosine deaminase?

Answer 1

Cladribine.

Question 2

What is the drug of choice in hairy cell leukemia and what drug class is it in?

Answer 2

Cladribine, a purine analogue.

Question 3

To what receptors does von Willebrand Factor bind?

Answer 3

GP Ib-IX receptors on the platelet membrane

Question 4

What test is used to measure vWF platelet aggregation?

Answer 4

Addition of Ristocetin; this produces poor platelet aggregation in patients with a vWF deficiency.

Question 5

What is the pharmacologic treatment for vWF deficiency?

Answer 5

Desmopressin (DDAVP) which stimulates vWF release from the endothelium.

Question 6

In a patient who ingested rat poison, what must be administered to prevent life threatening GI bleeding?

Answer 6

Fresh frozen plasma- this restores the clotting factors II, VII, IX, and X (vitamin K dependent factors) which are depleted by the poison. Vitamin K should also be given.

Question 7

Most anemias produce increased production of what blood parameter as a compensatory response?

Answer 7

Erythropoietin.

Question 8

What is the classic triad of symptoms in aplastic anemia?

Answer 8

Low hemoglobin, absent hematopoietic cells in the bone marrow, thrombocytopenia.

Question 9

In what conditions is an increased reticulocyte index seen?

Answer 9

Hemolytic or hemorrhagic anemia assuming normal bone marrow function. In aplastic anemia, it is low because there are few marrow progenitor cells.

Question 10

What is erythropoietin?

Answer 10

A hormone secreted by the kidneys to induce RBC formation.

Question 11

What cell surface glycoprotein may prevent the action of chemotherapeutic agents?

Answer 11

The human multidrug resistance (MDR1) gene codes for P-glycoprotein which is a transmembrane ATP dependent efflux pump protein that has broad specificity for hydrophobic compounds. It can reduce drug influx into the cytosol and can increase drug efflux from the cytosol preventing action of chemotherapeutic agents.

Question 12

What drug can be administered to reverse methotrexate toxicity?

Answer 12

Folinic acid (leucovorin)

Question 13

What is the function of leucovorin?

Answer 13

To rescue bone marrow, gastrointestinal, and other mucosal cells from toxicity following high dose methotrexate administration.

Question 14

What is a principle difference between Hepatitis C and Hepatitis B viruses?

Answer 14

Hep C is an RNA virus, Hep B is a DNA virus.

Question 15

Describe the difference in Hep. B and Hep C. liver toxicity.

Answer 15

Hepatitis B virus integrates its DNA into the host genome which increases risk for HCC. Hepatitis C is an RNA virus and lacks reverse transcriptase so does not integrate into the host genome.

Question 16

In patients with B12 deficiency, what is the most common means of supplement administration?

Answer 16

Parenterally; oral supplementation only corrects the deficiency in patients with insufficient intake. For most patients (with gastric atrophy, intrinsic factor deficiency, or terminal illeal disease), parenteral administration is required.

Question 17

Patients with repeated blood transfusions are likely to have buildup of what substance? And what form is this deposited in?

Answer 17

Iron buildup. Deposited as hemosiderin within tissues.

Question 18

What symptoms are characteristic of paroxysmal nocturnal hemoglobinuria (PNH)?

Answer 18

Hemolytic anemia, hypercoaguability, pancytopenia.

Question 19

What genetic mutation is associated with paroxysmal nocturnal hemoglobinuria?

Answer 19

Aquired PIGA gene mutation within a clonal population of multipotent hematopoietic stem cells. The gene is involved in glycosylphosphatidylinositol anchor (GPI) synthesis which is necessary for attachment of cell surface proteins including CD55 and CD59.

Question 20

What is the function of CD55?

Answer 20

Decay accelerating factor.

Question 21

What is the function of CD59?

Answer 21

MAC inhibitory protein.

Question 22

What deficiencies are present in patients with paroxysmal nocturnal hemoglobinuria?

Answer 22

CD55 and CD59 deficiency and deficiency in complement-mediated hemolysis.

Question 23

What complications are associated with paroxysmal nocturnal hemoglobinuria?

Answer 23

Budd chiari syndrome due to thrombotic complications, pancytopenia, aplastic anemia.

Question 24

How is Paroxysmal Nocturnal Hemoglobinuria diagnosed?

Answer 24

Flow cytometry will show absence of GPI anchor and CD55 and CD59 deficiency.

Question 25

Where are most coagulation factors synthesized?

Answer 25

In the liver.

Question 26

What coagulation factor has the shortest half life?

Answer 26

Factor VII, part of the extrinsic pathway.

Question 27

What coagulation factor is most likely to first become deficient in a patient with liver failure and what lab result will reflect this deficiency?

Answer 27

Factor VII deficiency resulting in prolonged PT.

Question 28

What lab value must be monitored in a patient taking warfarin?

Answer 28

PT (or INR).

Question 29

What is used to most rapidly reverse warfarin toxicity?

Answer 29

Fresh frozen plasma.

Question 30

What is implicated by presence of erythroid precursor cells in the liver and spleen?

Answer 30

Extramedullary hematopoiesis