Haptoglobin testing is used primarily to help detect and evaluate hemolytic anemia and to distinguish it from anemia due to other causes; however, it cannot be used to diagnose the cause of the hemolysis.
If a haptoglobin level is low or unexpectedly high, then testing may be repeated at a later time to evaluate changes in concentration.
If the haptoglobin is normal and the reticulocyte count is increased, then RBC destruction may be occurring in organs such as the spleen and liver (so-called extravascular hemolysis). Because the freed hemoglobin is not released into the bloodstream, the haptoglobin is not consumed and so is at a normal level.
If the haptoglobin concentration is normal and the reticulocyte count is not increased, then it is likely that the anemia present is not due to RBC breakdown.
If haptoglobin is decreased without any signs of hemolytic anemia, then it is possible that the liver is not producing adequate amounts of haptoglobin. This may be seen with liver disease, although haptoglobin is not typically used to diagnose or monitor liver disease.
Haptoglobin is considered an "acute-phase" protein; this means that it will be elevated in many inflammatory diseases, such as ulcerative colitis, acute rheumatic disease, heart attack, and severe infection. This can complicate the interpretation of the haptoglobin results. Haptoglobin testing is not generally used to help diagnose or monitor these conditions.
Drugs that can increase haptoglobin levels include androgens and corticosteroids. Drugs that can decrease haptoglobin concentrations include isoniazid, quinidine, streptomycin, and birth control pills.
This article was last reviewed on August 28, 2012. | This article was last modified on July 21, 2013.
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