Haptoglobin, Serum

CPT CODE:

USEFUL FOR:

Confirmation of intravascular hemolysis

SPECIMEN REQUIRED:

Draw blood in a plain, red-top tube(s) or a serum gel tube(s). Spin down and send 1 mL of serum refrigerated.

TRANSPORT TEMPERATURE:

Refrig\Frozen <14 days OK\Ambient <14 days OK

CLINICAL INFORMATION:

Haptoglobin  is an immunoglobulin-like plasma protein that bindshemoglobin. The haptoglobin-hemoglobin complex is removed from plasma by macrophages and the hemoglobin is catabolyzed.   When the hemoglobin-binding capacity of haptoglobin is exceeded, hemoglobin passes through the renal glomeruli, resulting in hemoglobinuria.  
Chronic intravascular  hemolysis causes persistently low haptoglobin concentration.  Regular strenuous exercise may cause sustained low haptoglobin, presumably from low-grade hemolysis. Low serumhaptoglobin may also be due to severe liver disease.
Neonatal plasma or serum specimens usually do not containmeasurable haptoglobin; adult levels are achieved by 6 months.
Increase in plasma haptoglobin concentration occurs as an acute-phase reaction.  Levels may appear to be increased in conditions suchas burns and nephrotic syndrome.  An acute-phase response may beconfirmed and monitored by assay of other acute-phase reactantssuch as alpha-1-antitrypsin and C-reactive protein.

CLINICAL INTERPRETATION:

Absence of plasma haptoglobin may therefore indicate intravascularhemolysis. However, congenital anhaptoglobinemia is common,particularly in African-Americans. For this reason, it may be difficultor impossible to interpret a single measurement of plasma haptoglobin.If the assay value is low, the test should be repeated after 1-2 weeksfollowing an acute episode of hemolysis. If all the plasma haptoglobinis removed following an episode of intravascular hemolysis, and ifhemolysis ceases, the haptoglobin concentration should return tonormal in a week.
Low levels of plasma haptoglobin may indicateintravascular hemolysis.

REFERENCE VALUES:

30-200 mg/dL