Question 146
A 44-year-old male with a history of alcohol use presents to his family physician with complaints of fatigue. Physical examination reveals an enlarged liver, but is otherwise unremarkable. Laboratory testing reveals:
Hemoglobin: 9.2 g/dL
Hematocrit: 27%
White blood cell count: 10.2 x 103 cells/mm3
Mean corpuscular volume: 107 fL
Platelet count: 300,000/mm3
Total bilirubin: 0.6 mg/dL
Direct: 0.2 mg/dL
Alkaline phosphatase: 142 U/L
AST: 245 U/L
ALT: 137 U/L
Gamma-glutamyltransferase: 250 U/L
Albumin: 2.8 g/dL
A peripheral smear of the blood is performed. Of the following red blood cell morphologies, which is most likely to be present?
A. Tear drop cells
B. Howell-Jolly bodies
C. Schistocytes
D. Burr cells
E. Reticulocytes
Answer for Question 146
Answer: D (Burr cells)
Explanation: The patient has liver disease, most likely related to his alcohol abuse, which is suggested by the history and the AST/ALT ratio. The patient also has an anemia, which is most likely due to decreased production, and therefore, reticulocytes are not likely to be present. Burr cells (and spur cells) are associated with liver disease. Target cells are associated with obstructive liver disease. Howell-Jolly bodies occur post-splenectomy or in patients with hyposplenism (e.g., sickle cell patients).
Question 147
A 24-year-old Asian male falls at work and sustains a fracture of his left fibula. In the emergency room, a complete blood cell count reveals:
Hemoglobin: 12.9 g/dL
Hematocrit: 38%
White blood cell count: 8.9 x 103 cells/mm3
Mean corpuscular volume: 66 fL
Platelet count: 300,000/mm3
He has no past medical history. He is released from the hospital with a cast. Follow-up laboratory testing performed four weeks later reveals:
Serum iron: 120 µg/dL
Total iron binding capacity: 402 µg/dL
Ferritin: 160 ng/mL
A hemoglobin electrophoresis reveals no abnormalities. Of the following, what is the most likely diagnosis?
A. α-thalassemia
B. β-thalassemia
C. Sickle cell anemia
D. Iron deficiency anemia
E. Anemia of chronic disease
Answer for Question 147
Answer: A (α-thalassemia)
Explanation: The patient has a markedly low MCV and only a mildly decreased hemoglobin. The serum iron, TIBC and ferritin concentrations are normal. Given he is a young otherwise healthy male, iron deficiency is very unlikely, and not supported by the laboratory testing. An asymptomatic thalassemia is possible. Given his Asian ancestry, an α-thalassemia would be most likely. In a hemoglobin electrophoresis, patients with α-thalassemia will be normal; patients with β-thalassemia would have an elevated amount of hemoglobin A2 and hemoglobin F. In sickle cell anemia, the hemoglobin electrophoresis would not be normal, and the patient does not have a chronic disease process (eliminating anemia of chronic disease).
Question 148
A 20-year-old Greek male college student slips and falls in the cafeteria, hitting his head. He is subsequently taken to the emergency room, where a complete blood cell count reveals:
Hemoglobin: 12.7 g/dL
Hematocrit: 37%
White blood cell count: 10.2 x 103 cells/mm3
Mean corpuscular volume: 67 fL
Platelet count: 290,000/mm3
He has no past medical history. He is released from the emergency room after a period of observation and a negative CT scan of the head. Follow-up laboratory testing performed four weeks later reveals:
Serum iron: 132 µg/dL
Total iron binding capacity: 356 µg/dL
Ferritin: 157 ng/mL
A hemoglobin electrophoresis reveals no abnormalities. Of the following, which is the most likely underlying genetic defect responsible for his red blood cell abnormality?
A. Gene deletion
B. Mutation in gene for hemoglobin resulting in no production
C. Mutation in gene for hemoglobin resulting in decreased production
D. Isochromosome
E. Translocation
Answer for Question 148
Answer: A (Gene deletion)
Explanation: The patient has a markedly low MCV and only a mildly decreased hemoglobin. The serum iron, TIBC, and ferritin concentrations are normal. Given he is a young otherwise healthy male, an asymptomatic thalassemia is possible. Given his Mediterranean ancestry, an α-thalassemia is possible. In a hemoglobin electrophoresis, patients with α-thalassemia will be normal; patients with β-thalassemia would have an elevated amount of hemoglobin A2 and hemoglobin F. The underlying cause of α-thalassemia is a gene deletion. β-thalassemia is due to a mutation in the hemoglobin gene that causes either no production or decreased production. Isochromosomes and chromosomal translocations are not normally associated with thalassemia.