Serum Haptoglobulin

Function

Haptoglobin is a protein produced by the liver that functions as a scavenger for free hemoglobin in the blood. When red blood cells (RBCs) are destroyed (hemolysis), they release hemoglobin into the plasma. Free hemoglobin is toxic and can cause kidney damage. Haptoglobin binds to this free hemoglobin, forming a complex that is rapidly cleared by the liver.

Why it is Ordered

Physicians order the Serum Haptoglobin test when they suspect a patient is suffering from hemolytic anemia. It is usually part of a 'hemolysis panel' which includes LDH, Bilirubin, and a Reticulocyte count. Symptoms that trigger this test include:

• Unexplained jaundice (yellowing of skin/eyes)
• Dark or tea-colored urine
• Fatigue and shortness of breath
• Pale skin (pallor)

Associated Conditions

Conditions affecting haptoglobin levels include:

• Autoimmune Hemolytic Anemia: The body's immune system destroys its own RBCs.
• Transfusion Reactions: Incompatibility between donor and recipient blood.
• Sickle Cell Disease or Thalassemia: Genetic disorders leading to abnormal RBC destruction.
• Malaria: A parasitic infection that ruptures red blood cells.
• Acute Phase Response: Since haptoglobin is also an acute-phase reactant, levels can rise during systemic inflammation or infection, potentially masking underlying hemolysis.