An acid glycoprotein
found in blood plasma
which, when it binds to free hemoglobin
in the blood
(i.e. not within a red blood cell
), cannot be filtered and eliminated from the body by the kidneys
. People with hemolytic
disorders (diseases that involve the destruction of red blood cells) have low serum levels of haptoglobin (the normal range is 0.5 - 3.2 g/L).
From the BioTech Dictionary at http://biotech.icmb.utexas.edu/. For further information see the BioTech homenode.