Deck XVI

Question 1

What is the pathophysiology associated with G6PD deficiency?

Answer 1

An X-linked erythrocyte enzyme deficiency of the hexose monophosphate pathway. NADPH produced in RBCs is low which impairs glutathione- mediated inactivation of free radicals. This induces hemolytic episodes as induced by infections, medications, and other oxidants.

Question 2

What type of anemia is implicated by schistocytes (fragmented RBCs) in a peripheral smear?

Answer 2

Microangiopathic hemolytic anemia

Question 3

Name five causes of microangiopathic hemolytic anemia.

Answer 3

HUS, TTP, DIC, malignant hypertension, metastatic carcinoma.

Question 4

What is the the underlying pathophysiology of hemolytic uremic syndrome?

Answer 4

Endothelial cell injury causes isolated activation of platelets and formation of microthrombi. RBCs are damaged when passing through mucrovascular channels and appear as schistocytes. The coagulation system is not activated thus PT and PTT are normal

Question 5

What is the characteristic pentad of symptoms in HUS and TTP?

Answer 5

Fever, neurologic manifestations, renal failure, thrombocytopenia, microangiopathic hemolytic anemia

Question 6

What are the principle epidemiological differences between HUS and TTP?

Answer 6

HUS occurs primarily in children and has renal involvement; TTP occurs most often in adults with predominant neurological symptoms. Fever, thrombocytopenia, microangiopathic hemolytic anemia are common in both conditions.

Question 7

What is the treatment for HUS and TTP?

Answer 7

Emergent plasmapheresis.

Question 8

What are metalloproteinases?

Answer 8

Zn containing enzymes that degrade extracellular matrix. They participate in normal tissue remodeling and in tumor invasion through the basement membrane and connective tissue.

Question 9

What is Immune thrombocytopenic purpura (ITP)?

Answer 9

An autoimmune disease characterized by the immune destruction of platelets by anti-platelet antibodies. In children it is typically acute and self limited while in adults it is often insidious and chronic. Tx is immunosuppression (steroids).

Question 10

What symptoms are associated with immune thrombocytopenic purpura?

Answer 10

Ecchymoses, petechiae, mucosal bleeding without signs and symptoms of TTP/HUS, pancytopenia, marrow failure or splenomegaly.

Question 11

What condition is indicated by red blood cells without central pallor?

Answer 11

Spherocytes. Indicate spherocytosis.

Question 12

What red cell index is most specific for spherocytosis?

Answer 12

Elevated mean corpuscular hemoglobin concentration (MCHC).

Question 13

What differentiates the presentation of CML from leukemoid reaction?

Answer 13

Both cause elevation of WBCs but neutrophil alkaline phosphatase level is elevated or normal in a leukamoid reaction but is decreased in CML.

Question 14

What is the difference in lab values between AML and CML?

Answer 14

In AML, myeloblasts are elevated; in CML, there are few blasts.

Question 15

What is the most important criteria for determining cancer prognosis?

Answer 15

Tumor stage (extent of tumor expansion)

Question 16

What is considered first line treatment for DVTs in pregnant women?

Answer 16

Heparin.

Question 17

What is the underlying pathology associated with mealoblastosis?

Answer 17

A defect in DNA synthesis. In chronic alcoholics this can result from a nutritional deficiency of folate which impairs synthesis of purine and pyrimidine bases.

Question 18

What do blast cells look like on peripheral smear?

Answer 18

Very large nucleated cells with scant cytoplasm.

Question 19

What is required for diagnosis of AML?

Answer 19

Greater or equal to 20% myeloblasts in the peripheral blood or marrow.

Question 20

What is a complication associated with massive transfusion of packed red blood cells (i.e. more than 5-6 L of blood)?

Answer 20

Chelation of serum calcium (and magnesium), causing hypocalcemia and parasthesias. This is caused by elevated plasma levels of citrate, a substance added to stored blood.

Question 21

In a patient with an intrinsic pathway clotting defect, administration of what agent will induce blood clotting?

Answer 21

Thrombin.

Question 22

What lab findings are characteristic of HUS?

Answer 22

Decreased RBC count, hematocrit, and platelet count, increased bleeding time, LDH, BUN, and creatinine.

Question 23

What is Polycythemia Vera?

Answer 23

A clonal myeloproliferative disease of pluripotent hematopoietic stem cells. JAK2 mutation renders hematopoietic stem cells more sensitive to growth factors.

Question 24

How does polycythemia vera present?

Answer 24

With increased RBC mass, increased plasma volume, low erythropoietin levels; elevated WBC count, thrombotic events (blood hyperviscosity), peptic ulceration, pruritus, gouty arthritis.

Question 25

What are common physical exam findings in a patient with polycythemia vera?

Answer 25

Plethoric, ruddy face and splenomeagly.

Question 26

What is the treatment for polycythemia vera?

Answer 26

Serial phlebotomy to keep hematocrit < 45%.

Question 27

What may cause increased hematocrit in patients with obstructive sleep apnea?

Answer 27

Release of erythropoietin into the bloodstream by peritubular cells in the renal cortex due to sensed hypoxia.

Question 28

Where are erythrocytes produced?

Answer 28

Induced by erythropoietin, production occurs in the bone marrow.

Question 29

What is hematocrit?

Answer 29

The percentage of the volume of whole blood that is composed of RBCs.

Question 30

In patients with high risk of developing DIC and progressive hypofibrinogenemia, what should be carefully monitored?

Answer 30

Serum fibrinogen and platelet count.