Haptoglobin

Hemoglobin is a protein in your red blood cells that carries oxygen from your lungs to the rest of your body. Most hemoglobin is found inside your red blood cells. When red blood cells die, they release hemoglobin. This results in small amounts of hemoglobin circulating in your bloodstream. Haptoglobin binds to the hemoglobin in your bloodstream, and then your liver removes it from the body.

Damaged red blood cells also release hemoglobin. So if your red blood cells are damaged or break down faster than usual, you will have more hemoglobin than usual in your bloodstream. That means haptoglobin will bind to all of this extra hemoglobin so that it can be cleared from your body. The haptoglobin may leave the body faster than your liver can make it. This causes your haptoglobin blood levels to drop. If your haptoglobin levels are too low, it may be a sign of a disorder of the red blood cells, such as anemia.

A low haptoglobin level is normal for infants less than six months old.

Otherwise, a haptoglobin level that is lower than normal may be a sign of a red blood cell disorder, while a level that is higher than normal may point to a different condition. Your provider may order other blood tests to help make a diagnosis.

Lower-than-normal haptoglobin can also be seen with liver disease and with certain infections such as mononucleosis. Higher-than-normal levels are often seen when the body is fighting inflammation or tissue damage.