Question 1

Hemorrhage and thrombosis are physiologic complications of __________ due to excessive proliferation of the megakaryocyte lineage.

Accepted Answer

Hemorrhage and thrombosis are physiologic complications of Thrombocythemia due to excessive proliferation of the megakaryocyte lineage. Thrombocytopenia, Hyperuricemia, and Hypercalcemia are not directly related to this complication.

Question 2

Which clinical manifestations in polycythemia vera are consistent with those of other myeloproliferative syndromes?

Accepted Answer

All of the above clinical manifestations (splenomegaly, myeloid metaplasia, and myelofibrosis) are consistent with other myeloproliferative syndromes, such as essential thrombocytosis and primary myelofibrosis.

Question 3

Which conditions are known to cause a possible false diagnosis of polycythemia vera?

Accepted Answer

Heavy smoking and alcoholic liver disease are known to cause an increase in red blood cell count, potentially leading to a false diagnosis of polycythemia vera. Systemic lupus erythematosus is not known to cause this condition.

Question 4

Which factors constitute a diagnosis of polycythemia vera by the polycythemia vera study group guidelines?

Accepted Answer

According to the polycythemia vera study group guidelines, a diagnosis of polycythemia vera requires the presence of all three factors: elevated red cell mass, normal arterial oxygen saturation, and splenomegaly. Therefore, choice D (All of the above) is the correct answer.

Question 5

Relative erythrocytosis can be differentiated from secondary erythrocytosis and polycythemia vera by what clinical feature(s)?

Accepted Answer

In relative erythrocytosis, there is an increase in red blood cell count, but the overall red cell mass is normal. This differentiates it from secondary erythrocytosis (caused by an underlying condition such as hypoxia or renal disease) and polycythemia vera, which both have an increase in red cell mass. Lung disease (A) and cyanosis (B) can be associated with hypoxia and secondary erythrocytosis, but are not specific to this type of erythrocytosis. Hepatomegaly (C) and a normal LAP (E) are not specific features of any type of erythrocytosis.

Question 6

In both absolute erythrocytosis and relative erythrocytosis the hematocrit is __________.

Accepted Answer

Both absolute and relative erythrocytosis result in an increased hematocrit, so options A and C can be eliminated. Option D is incorrect as it includes all possible choices, while option E is incorrect as there should be at least one correct choice. Therefore, the correct answer is B.

Question 7

Dehydration is an example of __________ erythrocytosis.

Accepted Answer

Dehydration causes an increase in the concentration of erythrocytes in the blood, but not necessarily an increase in the actual number of erythrocytes. This is an example of relative erythrocytosis, as opposed to absolute erythrocytosis where there is a true increase in the number of erythrocytes in the blood. Secondary and primary erythrocytosis refer to underlying medical conditions that cause an increase in erythrocytes.

Question 8

Polycythemia vera is characterized by:

Accepted Answer

Polycythemia vera is characterized by the excessive proliferation of myeloid and megakaryocytic elements of the bone marrow, leading to an increase in erythrocytes, leukocytes, and platelets. There is an accelerated erythropoiesis, which results in an increase in red blood cells, leading to hyperviscosity of the blood, and the formation of blood clots can occur.

Question 9

In polycythemia vera, therapeutic phlebotomies reduce the total red cell mass by removing 350-500 mL over 2-3 days until the hematocrit is maintained at __________ percent.

Accepted Answer

Therapeutic phlebotomies in polycythemia vera aim to maintain the hematocrit at 40-45%. Higher hematocrit levels increase the risk of thrombotic events, while lower levels may cause anemia and organ damage. Therefore, maintaining the hematocrit at this level is optimal for patient outcomes.

Question 10

What is the objective of polycythemia vera therapy?

Accepted Answer

The objective of polycythemia vera therapy is to reduce the total red cell mass, as this condition is characterized by an overproduction of red blood cells that can lead to complications like blood clots. Cytotoxic myelosuppression can also be used to control malignancy associated with polycythemia vera. Therefore, reducing total red cell mass and controlling malignancy are important objectives of therapy for polycythemia vera.

Question 11

The clinical features of polycythemia vera are attributed to the excessive proliferation of which cell line(s)?

Accepted Answer

Polycythemia vera is characterized by the excessive proliferation of all three cell lines: erythrocytes, platelets, and granulocytes, leading to its clinical features.

Question 12

Common physical findings in polycythemia vera include:

Accepted Answer

Polycythemia vera is characterized by increased red blood cell mass, which can lead to several physical findings. Facial plethora, or facial redness, is a common finding in patients with polycythemia vera due to increased blood flow to the face. Pruritus or itching is another common finding due to the release of histamine from increased basophils. Cerebral circulating disturbances, such as headaches or dizziness, can also occur due to the increased blood volume causing pressure on blood vessels. Thrombotic episodes or blood clots are a significant concern in polycythemia vera due to the increased viscosity of the blood. Therefore, all of the above options are common physical findings in polycythemia vera.

Question 13

In polycythemia vera, erythropoietin is __________.

Accepted Answer

In polycythemia vera, erythropoietin levels are typically decreased. This is because the body is producing too many red blood cells even without the normal stimulus provided by erythropoietin, leading to a feedback inhibition that reduces erythropoietin production.

Question 14

Polycythemia vera has an insidious onset and is most often discovered through a __________ determination.

Accepted Answer

Polycythemia vera is characterized by an increase in red blood cell mass, which is reflected by an elevated hematocrit level. Other lab values such as WBC count, reticulocyte count, and platelet count may also be elevated in some cases, but the hematocrit is the most reliable indicator of polycythemia vera. Electrophoresis may be used to distinguish between different types of polycythemia, but it is not typically the first test used to diagnose the condition.

Question 15

The presence of splenomegaly in patients with polycythemia vera is due to __________.

Accepted Answer

Splenomegaly in polycythemia vera is primarily due to extramedullary hematopoiesis, which occurs as a compensatory mechanism as a result of increased red cell mass in the bone marrow. This can cause an enlargement of the spleen as it tries to take over some of the hematopoietic function from the overloaded bone marrow. Intramedullary hematopoiesis (A) refers to normal hematopoietic activity within the bone marrow. Erythrocytopenia (C) is the opposite of polycythemia vera and refers to a decrease in red blood cells. Myeloid metaplasia (D) is a rare complication of polycythemia vera in which the bone marrow is replaced by fibrous tissue.

Question 16

A patient presents with a hematocrit of 55%, elevated red cell mass, normal arterial oxygen saturation, elevated LAP score, and thrombocytosis. What is the most probable cause of these laboratory findings?

Accepted Answer

The combination of elevated hematocrit, elevated red cell mass, normal arterial oxygen saturation, elevated LAP score, and thrombocytosis strongly suggests the diagnosis of polycythemia vera. Secondary erythrocytosis and relative erythrocytosis can also cause an elevated hematocrit, but they would not be associated with thrombocytosis and elevated LAP score. Idiopathic myelofibrosis would present with a normal or decreased red cell mass, and essential thrombocythemia would have a normal red cell mass with thrombocytosis.

Question 17

Rapid reduction of the blood volume to normal can be accomplished by __________.

Accepted Answer

Therapeutic phlebotomy is the process of removing a specific amount of blood from the patient's body to reduce their blood volume to a normal level. This can be an effective treatment for medical conditions that cause an excessive amount of red blood cells or iron to build up in the body, such as polycythemia vera or hemochromatosis. Blood transfusion, plasmapheresis, chemotherapy, and bone marrow transplant are not appropriate treatments for rapidly reducing blood volume to normal levels.

Question 18

Tissue hypoxia and increased erythropoietic activity is an example of ___________ erythrocytosis.

Accepted Answer

Tissue hypoxia and increased erythropoietic activity are secondary causes of erythrocytosis, as they are caused by an underlying condition that stimulates the production of erythrocytes. Relative erythrocytosis is a result of a decrease in plasma volume, while primary erythrocytosis is caused by a genetic mutation in the stem cells of the bone marrow. Stress erythrocytosis is not a recognized category of erythrocytosis.

Question 19

What is the etiology of polycythemia vera?

Accepted Answer

Polycythemia vera is a clonal hematologic malignancy of bone marrow, which results in the overproduction of red blood cells, white blood cells, and platelets. It is caused by a mutation in the JAK2 (Janus kinase 2) gene, leading to uncontrolled growth and proliferation of hematopoietic cells.

Question 20

What is the usefulness of myelosuppression as a treatment in polycythemia vera?

Accepted Answer

Myelosuppression, through the use of drugs like hydroxyurea, suppresses the abnormal bone marrow proliferation seen in polycythemia vera, reducing the excessive production of red blood cells, white blood cells, and platelets. This in turn can alleviate symptoms like pruritus, control spleen size, and reduce the risk of thrombotic events. Therefore, all of the choices are correct.

Quiz 18: Chronic Myeloproliferative Disorders Ii: Polycythemia Vera, Essential Thrombocythemia, and Idiopathic Myelofibrosis