Chapter 14 Study Guide Flashcards
Which is the most common cause of microcytic hypochromic anemia in American women aged 20 to 50 years?
A. autoimmune hemolysis B. iron deficiency C. Vitamin B12 deficiency D. thalassemia minor E. viral infection
B
Iron deficiency resulting from the monthly loss of iron in menstrual blood is the most common cause of microcytic hypochromic anemia.
The most common form of autosomal dominant hereditary spherocytosis is caused by a mutation of the gene encoding which of the following proteins?
A. Ankyrin B. Spectrin C. Protein 4.1 D. Hemoglobin A E. Transferrin
A
The most common form of autosomal dominant hereditary spherocytosis is caused by a mutation of the ankyrin gene. However, a deficiency of spectrin, which may be primary or secondary due to another defect, is found in most forms of hereditary spherocytosis, making it the most common biochemical abnormality in this disease.
Aplastic crisis, which can be encountered in patients with hereditary spherocytosis or sickle cell anemia, is most often precipitated by
A. deficiency of erythropoetin
B. negative feedback inhibition by bilirubin
C. adverse effect of iron released from hemolyzed erythrocytes
D. autoimmune mechanisms
E. parovirus infection
E. Parovirus infection
Aplastic crisis in hereditary spherocytosis or sickle cell
anemia is usually triggered by parvovirus infection. The virus infects and destroys the red blood cell precursors in the bone marrow
The deletion of two α-globin chains of hemoglobin is the cause of
A. α-thalassemia trait B. α-thalassemia minor C. salient carrier state D. hemoglobin H disease E. hydrops fetalis
A
Deletion of two α-globin genes is found in patients who have α-thalassemia trait. These patients, like those who have ß-thalassemia minor, are asymptomatic.
Normocytic normochromic anemia, associated with low serum iron, reduced total-iron binding capacity, and abundant iron stores, as seen in the bone marrow biopsy, are laboratory findings typically found in anemia of
a. iron deficiency
b. chronic disease
c. thalassemia minor
d. thalassemia trait
e. vitamin B12 deficiency
B,
Anemia of chronic disease is typically normocytic, hypochromic, and associated with hypoutilization of iron, reflected in abundant iron stores and reduced total iron-binding capacity.
The most common cause of myelophthisic anemia is
a. metastatic carcinoma to the bones
b. multiple myeloma
c. lymphoma
d. leukemia
e. osteosclerosis
A,
Myelophthisic anemia, resulting from the destruction and replacement of the hematopoietic bone marrow by other cells, is most often caused by metastatic carcinomas. These tumors usually originate from primary cancers in the breast, lung, or prostate.
Which test is abnormal in hemophilia A?
a. Bleeding
b. Platelet count
c. Prothrombin time
d. Partial thromboplastin time
e. Clot retraction
D
Hemophilia A results from a deficiency of clotting factor VIII, which participates in the intrinsic coagulation pathway. Partial thromboplastin time provides information about the intrinsic pathway components and is thus prolonged in hemophilia A and hemophilia B.
What are the mechanisms of thrombocytopenia in patients who have giant hemangiomas?
a. Autoimmune destruction of platelets
b. Inhibition of bone marrow
c. Mechanical destruction of platelets
d. Increased consumption of platelets in peripheral blood vessels
e. Disseminated intravascular hemolysis
C
The turbulent blood flow through the giant hemangiomas promotes mechanical destruction of platelets.
Hemolytic uremic syndrome (HUS) shares many features with thrombotic thrombocytopenic purpura (TTP), but in contrast with patients with TTP, those with HUS do NOT have
a. anemia
b. renal failure
c. neurologic deficits
d. fever
e. thrombocytopenia
C,
Hemolytic uremic syndrome (HUS) most commonly develops following a gastrointestinal infection caused by verotoxin-producing Escherichia coli O157:H7. It resembles thrombotic thrombocytopenic purpura (TTP), but in contrast to TTP, HUS does not cause neurologic deficits.
Which of the following bleeding tests is abnormal in patients with von Willebrand disease?
a. Prolonged bleeding time
b. Thrombocytopenia
c. Prolonged prothrombin time
d. Shortened partial thromboplastin time
e. Increased levels of factor VIII in plasma
A,
A deficiency of the von Willebrand factor (vWF) in this disease, which carries the same name, affects the ability of platelets to participate in hemostasis. The bleeding time, which was designed to measure the function of platelets and blood vessels, is thus prolonged. Because vWF interacts with factor VIII, partial thromboplastin time is also prolonged and the concentration of factor VIII in blood is reduced.
Severe hemophilia develops in patients who have factor VIII reduced below
a. 1%
b. 5%
c. 10%
d. 20%
e. 25%
A,
Severe hemophilia occurs only in patients who have less than 1% of the normal concentration of factor VIII. Levels in the range of 2% to 5% are associated with moderate hemophilia, whereas patients who have 6% to 15% of the normal levels have mild hemophilia.
