Part I: Anemia and Red Cell Disorders
Which of the following laboratory tests would be least informative for establishing the presence of ineffective erythropoiesis in a patient with anemia?
A. Serum lactate dehydrogenase level
D. Serum erythropoietin level
E. Bone marrow examination
The serum erythropoietin level is high in all patients with anemia, whereas the other choices are all informative in identifying patients with ineffective erythropoiesis. The serum lactate dehydrogenase (LDH) will be high owing to release of this enzyme from marrow erythroid cells undergoing destruction. The serum (unconjugated) bilirubin will be high owing to breakdown of hemoglobin heme. The reticulocyte count will be low because few red cells are emerging from the disordered marrow. The bone marrow will show erythroid hyperplasia with some type of defect in erythroid maturation. (The answer is D.)
Which of the following combinations of laboratory test values best supports the presence of hemolysis?
A. Low lactate dehydrogenase, high unconjugated bilirubin, low haptoglobin
B. Low lactate dehydrogenase, high unconjugated bilirubin, high haptoglobin
C. High lactate dehydrogenase, high unconjugated bilirubin, low haptoglobin
D. High lactate dehydrogenase, high conjugated bilirubin, low haptoglobin
E. High lactate dehydrogenase, high conjugated bilirubin, high haptoglobin
Serum LDH will be high owing to release of this enzyme from red cells undergoing destruction in the circulation. Unconjugated bilirubin will be elevated owing to increased heme catabolism. In contrast, conjugated bilirubin will be normal unless there is concurrent liver disease. Haptoglobin is an abundant plasma protein that has specific high-affinity binding to hemoglobin. During hemolysis excess hemoglobin is released from defective circulating red cells. The hemoglobin-haptoglobin complex is rapidly cleared from the circulation. (The answer is C.)
Which of the following provides the anemic patient with the most effective compensation for the deficit in red cell mass?
A. Increased resting cardiac output
B. Increased red cell 2,3-diphosphoglycerate level and decreased red cell oxygen affinity
C. Increased red cell adenosine triphosphate level and increased red cell oxygen affinity
D. Increased plasma erythropoietin level
E. Increased arterial oxygen tension (pO2)
As shown in Figure 3-4, the “right shift” in ...