Haptoglobin

🔬 Key Clinical Significance

1. Intravascular Hemolysis

↓ Haptoglobin (markedly reduced or absent)

Free hemoglobin released into plasma binds haptoglobin → complex cleared

Seen in:

Hemolytic anemias

Hemolytic transfusion reactions

Paroxysmal nocturnal hemoglobinuria (PNH)

Mechanical hemolysis (prosthetic heart valves)

👉 Low haptoglobin is a key marker of intravascular hemolysis

2. Extravascular Hemolysis

Normal or mildly decreased haptoglobin

RBCs destroyed mainly in spleen/liver → minimal free plasma hemoglobin

3. Acute-Phase Reactant

↑ Haptoglobin in:

Acute inflammation

Infection

Tissue injury

Malignancy

⚠️ May mask hemolysis if both hemolysis and inflammation coexist.

4. Liver Disease

↓ Haptoglobin due to reduced hepatic synthesis

Seen in:

Chronic liver disease

Severe hepatic failure

5. Differentiation of Jaundice

Hemolytic jaundice → ↓ haptoglobin

Hepatocellular / obstructive jaundice → normal or ↑ haptoglobin

📊 Associated Laboratory Findings in Hemolysis

↓ Haptoglobin

↑ Lactate dehydrogenase (LDH)

↑ Indirect (unconjugated) bilirubin

↑ Reticulocyte count

Hemoglobinemia / hemoglobinuria (in intravascular hemolysis)

🧠 Clinical Summary

• Low haptoglobin → intravascular hemolysis or liver disease
• Normal haptoglobin → extravascular hemolysis
• High haptoglobin → inflammation / acute-phase response