Which of the following test results suggest red blood cell (RBC) survival is significantly decreased from the

a. Decreased glycated hemoglobin
b. A T1/2 Cr of 30 days
c. Normal haptoglobin
d. Decreased lactic dehydrogenase

ANS: A
Glycated hemoglobin increases over the life of the red cell as it (the red cell and thus hemoglobin) is continually exposed to glucose in plasma. In hemolytic disease, the red cells have a shortened survival and thus less exposure to glucose, which results in a lower glycated hemoglobin than normal. Haptoglobin is an acute phase protein and may be normal or even increased even in intravascular hemolysis if the patient has concurrent inflammation; thus a normal haptoglobin does not rule out intravascular hemolysis with a shortened RBC survival. Lactic dehydrogenase is released from lysed red cells and increases when RBC survival is shortened. A T1/2 Cr of 30 days is normal.