Haptoglobin

Some laboratories use 0.5 to 2.2 g/L; newborns have very little; a small number of people of African ancestry make none at all; use the range your lab printed.

Haptoglobin is a protein made by the liver whose job is to mop up haemoglobin that has leaked out of broken red blood cells. When red cells are being broken down faster than usual, the haptoglobin is used up and the level in the blood falls. The test measures how much is left in circulation.

It is one of the tests doctors use when they are looking into whether red blood cells are being broken down early (haemolysis), usually alongside the reticulocyte count, bilirubin, lactate dehydrogenase and blood film.

• Inflammation or infection from any cause, because it is also an acute phase protein
• Some cancers
• Steroid medicines
• Tissue damage, including after surgery
• Nephrotic syndrome, a kidney condition

• Conditions where red cells are broken down early, including some inherited red cell conditions, some autoimmune conditions and mechanical heart valves
• Liver disease, because less is made
• A recent blood transfusion reaction
• Some medicines and some infections such as malaria
• An inherited absence of haptoglobin, seen in a small number of people

• A sample that has haemolysed in the tube (red cells broken during collection) reads low; the laboratory usually comments
• Any recent infection or inflammation raises it and can mask a low value
• Strenuous endurance exercise, such as a marathon, lowers it for a day or two
• Oestrogen-containing medicines lower it slightly

No fasting needed. Read together with the other markers of red cell breakdown; a single low value is not informative on its own.

Written by a UK consultant physician. Typical UK adult reference ranges; your laboratory's own printed range takes precedence.