The presence of hemoglobinuria, hemosiderinuria, and hemoglobinemia indicate that hemolysis is:

a. Severe
b. Acquired
c. Compensated
d. Intravascular

ANS: D
When hemolysis is intravascular, red cells are lysed within the circulation releasing hemoglobin; this is called hemoglobinemia. If the renal threshold is exceeded, then some hemoglobin may pass through the kidney and thus be found in urine (i.e., hemoglobinuria). Renal tubular epithelial cells where the iron is separated from protoporphyrin take up some hemoglobin passing through the kidney. Some of these renal tubular epithelial cells will gradually be sloughed off into the urine; an iron-specific stain will demonstrate the presence of iron in the form of hemosiderin (as in hemosiderinuria).