CHAPTER 25: EXTRINSIC DEFECTS LEADING TO INCREASED ERYTHROCYTE DESTRUCTION - NONIMMUNE CAUSES Flashcards
(1) Which one of the following is a feature found in all microangiopathic hemolytic anemias?
a. Pancytopenia
b. Thrombocytosis
c. Intravascular RBC fragmentation
d. Prolonged prothrombin time and partial thromboplastin time
c. Intravascular RBC fragmentation
(2) Typical laboratory findings in TTP and HUS include:
a. Schistocytosis and thrombocytopenia
b. Anemia and reticulocytopenia
c. Reduced levels of lactate dehydrogenase and aspartate aminotransferase
d. Increased levels of free plasma hemoglobin and serum haptoglobin
a. Schistocytosis and thrombocytopenia
(3) The pathophysiology of idiopathic TTP involves:
a. Shiga toxin damage to endothelial cells and obstruction of small blood vessels in glomeruli
b. Formation of platelet-VWF thrombi due to autoantibody inhibition of ADAMTS-13
c. Overactivation of the complement system and endothelial cell damage due to loss of regulatory function
d. Activation of the coagulation and fibrinolytic systems with fibrin clots throughout the microvasculature
b. Formation of platelet-VWF thrombi due to autoantibody inhibition of ADAMTS-13
(4) Which of the following tests yields results that are abnormal in DIC but are usually within the reference interval or just slightly abnormal in TTP and HUS?
a. Indirect serum bilirubin and serum haptoglobin
b. Prothrombin time and partial thromboplastin time
c. Lactate dehydrogenase and aspartate aminotransferase
d. Serum creatinine and serum total protein
b. Prothrombin time and partial thromboplastin time
(5) Which one of the following laboratory results may be seen in BOTH traumatic cardiac hemolytic anemia and exercise-induced hemoglobinuria?
a. Schistocytes on the peripheral blood film
b. Thrombocytopenia
c. Decreased serum haptoglobin
d. Hemosiderinuria
c. Decreased serum haptoglobin
(6) Which of the following species of Plasmodium produce hypnozoites that can remain dormant in the liver and cause a relapse months or years later?
a. P. falciparum
b. P. vivax
c. P. knowlesi
d. P. malariae
b. P. vivax
(7) Which one of the following is not a mechanism causing anemia in P. falciparum infections?
a. Inhibition of erythropoiesis
b. Lysis of infected RBCs during schizogony
c. Competition for vitamin B12 in the erythrocyte
d. Immune destruction of noninfected RBCs in the spleen
c. Competition for vitamin B12 in the erythrocyte
(8) Which Plasmodium species is widespread in Malaysia, has
RBCs with multiple ring forms, has band-shaped early trophozoites, shows a 24-hour erythrocytic cycle, and can
cause severe disease and high parasitemia?
a. P. falciparum
b. P. vivax
c. P. knowlesi
d. P. malariae
c. P. knowlesi
(9) One week after returning from a vacation in Rhode Island, a 60-year-old man experienced fever, chills, nausea, muscle aches, and fatigue of 2 days’ duration. A complete blood count (CBC) showed a WBC count of 4.5 x 10^9/L, hemoglobin level of 10.5 g/dL, a platelet count of 134 x 10^9/L, and a reticulocyte count of 2.7%. The medical laboratory scientist noticed tiny ameboid ring forms in some of the RBCs and some tetrad forms in others. These findings suggest:
a. Bartonellosis
b. Malaria
c. Babesiosis
d. Clostridial sepsis
c. Babesiosis
(10) What RBC morphology is characteristically found within the first 24 hours following extensive burn injury?
a. Macrocytosis and polychromasia
b. Burr cells and crenated cells
c. Howell-Jolly bodies and bite cells
d. Schistocytes and microspherocytes
d. Schistocytes and microspherocytes
(11) A 36-year-old woman was brought to the emergency department by her husband because she had experienced a seizure. He reported that she had been well until that morning, when she complained of a sudden headache and malaise. She was not taking any medications and had no history of previous surgery or pregnancy. Laboratory studies showed a WBC count of 15 x 10^9/L, hemoglobin level of 7.8 g/dL, a platelet count of 18 x 10^9/L, and schistocytes and helmet cells on the peripheral blood film. Chemistry test results included markedly elevated serum lactate dehydrogenase activity and a slight increase in the level of total and indirect serum bilirubin. The urinalysis results were positive for protein and blood, but there were no RBCs in the urine sediment. Prothrombin time and partial thromboplastin time were within the reference interval. When the entire clinical and laboratory picture is considered, which of the following is the most likely diagnosis?
a. HUS
b. HELLP syndrome
c. TTP
d. Exercise-induced hemoglobinuria
c. TTP
