Haptoglobin
Background
- Plasma protein that binds free hemoglobin released from lysed red blood cells
- Consumed in hemolysis, making it a useful marker
Normal Values
- Normal: 30-200 mg/dL
Interpretation
- Low or undetectable haptoglobin: hemolysis (intravascular > extravascular)
- Hemolysis workup: low haptoglobin + elevated LDH + elevated indirect bilirubin + elevated reticulocyte count + peripheral smear
- Haptoglobin is an acute-phase reactant (may be falsely normal in hemolysis if concurrent inflammation)
- Also low in liver disease (decreased production) and massive transfusion