Haptoglobin: what it is, what it tells you and when it’s tested

Haptoglobin is a protein made by your liver. Its job is to catch the haemoglobin that leaks out of red cells when they break. In doing so it gets used up: if many red cells break, haptoglobin falls.

When it’s tested

Doctors order it when they suspect haemolytic anaemia, meaning red cells that break down too fast. For example with anaemia and high indirect bilirubin, with a high LDH, or with artificial heart valves.

It is not a routine test for people who feel well. Without anaemia or other signs of haemolysis, its value says little.

That is why Rosa does not test it. Instead it measures haemoglobin and red cells, total, direct and indirect bilirubin, and ferritin, which show whether there is anaemia and whether red cells are breaking down.

What it tells you, and what it does not

If it is low, red cells are breaking down faster than usual, especially inside the blood vessels. The lower it is, the more likely.

It is not perfect. Haptoglobin also rises with inflammation, so an infection can push it back into range and hide haemolysis. It also falls if the liver makes too little.

That is why it is never read on its own.

That is why it is read together with other tests:

• Haemoglobin: It shows whether there is anaemia
• Bilirubin: The indirect part rises when red cells break down
• LDH: It rises when red cells break down
• Reticulocytes: They rise as the marrow replaces broken cells
• CRP: It shows whether inflammation is pushing it up

Normal haptoglobin levels

The lab decides what is normal. Many lab reports give 30 to 200 mg/dL. Your own report may print different limits: its range is what counts.

Below 25 mg/dL, especially with anaemia too, haemolysis becomes likely.

It is low in newborns and reaches adult levels in the first months of life. Some people make little of it for inherited reasons, with no problem at all.

What your result means

Find the row for your result, in mg/dL. Which values need a doctor? Below 30, especially with anaemia.

• Below 30: Low. Often red cells are breaking down faster than usual. It can also come from the liver, or from low production for inherited reasons. Talk to your doctor: they usually look at haemoglobin, LDH, bilirubin and reticulocytes.
• 30 to 200: Normal. Usually no sign of red cells breaking down. Nothing to do. If there is inflammation, your doctor knows it can hide mild haemolysis.
• Above 200: High. Usually an inflammation or infection under way. On its own it says little. Look at your CRP and how you feel. When the inflammation settles, it comes down on its own.

If your haptoglobin is high or low

• Low haptoglobin: Usually red cells are breaking down faster than usual. Sometimes it is the liver, or an inherited low production.
• High haptoglobin: Usually inflammation or an infection. It comes down on its own when that passes.

The most common causes

The causes depend on the direction.

• Low: haemolysis: Red cells breaking down from inherited, autoimmune, medicine-related or infectious causes, or because of an artificial heart valve.
• Low: liver: If the liver works poorly, it makes less.
• Low: inherited: Some people make little of it all their life, with no consequences.
• High: inflammation: Infections, inflammatory diseases, injuries and surgery raise it, like CRP.

What can skew the result

A few things move it without changing what is really happening to your red cells.

• Ongoing inflammation: It can raise it enough to hide mild haemolysis.
• The liver: Liver disease lowers it even without haemolysis.

When to worry

Talk to your doctor if:

• Your haptoglobin is low and you also have anaemia.
• It is low together with a high LDH or high indirect bilirubin.
• You feel tired and short of breath, your skin or eyes look yellow or your urine is dark.
• You have an artificial heart valve and these symptoms appear.
• You have very dark urine with marked weakness, fainting or sudden shortness of breath: call 112 or go to the emergency department.

Frequently asked questions

What are normal haptoglobin levels? Many lab reports give 30 to 200 mg/dL. The range on your own report is what counts.

Low haptoglobin: what does it mean? Usually that red cells are breaking down faster than usual. It can also come from the liver or an inherited low production. Your doctor reads it with haemoglobin, LDH, bilirubin and reticulocytes.

High haptoglobin: should I worry? Usually not. It rises with inflammation, like CRP. If you feel well, it comes down when the inflammation passes.

Do I need to fast for a haptoglobin test? It is not usually required. Follow the lab’s instructions anyway, as it is often done with other tests.

Does Rosa test haptoglobin? No. Rosa measures haemoglobin, bilirubin and ferritin, which show whether there is anaemia and whether red cells are breaking down. If your doctor wants haptoglobin, they order it separately.

Sources

• Niguarda Hospital, Milan, laboratory test catalogue: haptoglobin, reference values and meaning. Ospedale Niguarda, esami di laboratorio
• Marchand and colleagues, the predictive value of serum haptoglobin in hemolytic disease. JAMA, 1980. PMID 7365971
• Barcellini and Fattizzo, clinical applications of hemolytic markers in the differential diagnosis and management of hemolytic anemia. Disease Markers, 2015. PMID 26819490