Other names: Haemoglobin-Binding Protein; HPT; Hp

Haptoglobin is a protein, which is produced by the liver. The role of haptoglobin is to attach to free haemoglobin in the blood; once the proteins have joined together, they will be processed by the liver and the iron will be removed and recycled by the body.

Why is the test used?

The test is primarily used to diagnose and monitor haemolytic anaemia, which occurs when the red blood cells have a much shorter life span than normal; it cannot be used to determine the cause of the condition but it can be useful as a diagnostic tool for doctors. The test is used to distinguish haemolytic anaemia from other forms of the condition.

The test is usually ordered when a patient has symptoms of anaemia, including:

  • Pale skin
  • Tiredness
  • Weakness
  • Jaundice
  • Lethargy
  • Dark urine (this is a symptom of haemolytic anaemia)

The test may also be ordered if the patient has abnormal haemoglobin, red blood cell and haemocrit test results; the test is usually ordered alongside other tests, such as a blood film.

The test may also be repeated to monitor the patient’s condition.

How is the test done?

The test is done by taking a sample of blood from a vein in the arm (usually a vein on the inside of the elbow is used, as these are usually more prominent); a needle is inserted into the vein, the blood is drawn out and collected in a syringe. Once the sample has been collected, it will be bottled, labelled with the patient’s name and then sent away to the laboratory for testing.

What do the test results mean?

If levels of haptoglobin are low, red blood cell count is low and the reticulocyte count is high, this generally means that the patient has got haemolytic anaemia; levels of haemoglobin and haemocrit will also be lower than normal.

If levels of haptoglobin are normal but the reticulocyte count is higher than normal, this may indicate that the destruction of red blood cells is taking place inside the organs (including the liver and spleen).

If levels of haptoglobin and the reticulocyte count are normal, this indicates that the patient has a form of anaemia, which is not caused by destruction of the red blood cells.

If levels of haptoglobin are lower than normal but the patient does not have symptoms of haemolytic anaemia, this may indicate that the liver is not producing enough haptoglobin.

Haptoglobin is an acute-phase reactant, meaning that levels will increase in response to several different conditions, including inflammatory conditions and severe infections. Certain medications, including androgens and corticosteroids, may also increase haptoglobin levels. Medications, including oral contraceptives and streptomycin, may decrease levels of haptoglobin.

Specific Blood Tests

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