Haptoglobin
Haptoglobin is a scavenger protein that binds free haemoglobin released by destroyed red cells. A very low value is the single most sensitive blood marker of haemolytic anaemia.
What it measures
Haptoglobin is a liver-synthesized protein whose job is to mop up free haemoglobin spilled into circulation when red blood cells are destroyed. Each round of haemolysis consumes haptoglobin faster than the liver can resupply it, so the level falls and can drop to nearly zero in active haemolysis. Combined with elevated LDH, elevated indirect bilirubin and elevated reticulocyte count, low haptoglobin completes the textbook haemolysis tetrad.
What a high value can mean
- Acute-phase reaction — infection, inflammation, surgery, trauma; haptoglobin is a positive acute-phase reactant.
- Steroid therapy, nephrotic syndrome — modest rises.
- High haptoglobin can mask coexisting mild haemolysis — clinical correlation matters.
What a low value can mean
- Intravascular haemolysis — autoimmune haemolytic anaemia, mechanical valve, microangiopathic anaemia (TTP/HUS/DIC), sickle cell crisis, severe G6PD deficiency.
- Extravascular haemolysis — milder drops; spleen-driven red-cell destruction.
- Severe liver disease — synthesis fails.
- Congenital haptoglobin deficiency — rare.
When to discuss with a doctor
Haptoglobin <30 mg/dL alongside symptoms of anaemia or jaundice should be evaluated by your clinician — it is one of the most specific lab signals of haemolysis and warrants further work-up (LDH, peripheral smear, Coombs test). Mediora.AI surfaces the haemolysis pattern when present.