A plasma sample appears hemolyzed or red. Which of the following is true?

a. The patient has extravascular hemolysis.
b. The patient has increased haptoglobin.
c. The patient has increased hemopexin.
d. The plasma hemoglobin is greater than 50 mg/dL.

ANS: D
Plasma hemoglobin can be detected when the concentration of hemoglobin is greater than 50 mg/dL. Free hemoglobin is seen in plasma, giving it its red color when excessive intravascular hemolysis exists. Both haptoglobin and hemopexin will be decreased as an attempt to salvage iron occurs.