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Unit Code 9168:
Haptoglobin, Serum

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Useful For

Confirmation of intravascular hemolysis

Clinical Information

Haptoglobin  is an immunoglobulin-like plasma protein that binds

hemoglobin. 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 serum

haptoglobin may also be due to severe liver disease.

 

Neonatal plasma or serum specimens usually do not contain

measurable 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 such

as burns and nephrotic syndrome.  An acute-phase response may be

confirmed and monitored by assay of other acute-phase reactants

such as alpha-1-antitrypsin and C-reactive protein.

Reference Values

30-200 mg/dL

Interpretation

Absence of plasma haptoglobin may therefore indicate intravascular

hemolysis. However, congenital anhaptoglobinemia is common,

particularly in African-Americans. For this reason, it may be difficult

or impossible to interpret a single measurement of plasma haptoglobin.

If the assay value is low, the test should be repeated after 1-2 weeks

following an acute episode of hemolysis. If all the plasma haptoglobin

is removed following an episode of intravascular hemolysis, and if

hemolysis ceases, the haptoglobin concentration should return to

normal in a week.

 

Low levels of plasma haptoglobin may indicate

intravascular hemolysis.

Cautions

Low haptoglobin is normal for the first 3-6 months of life.

 

Haptoglobin is an acute-phase reactant and increases

with inflammation or tissue necrosis.

Clinical Reference

1.   Silverman LM: Amino aicds and proteins. In Tietz Textbook of Clinical

      Chemistry. Edited by NW Tietz. Philadelphia, WB Saunders Company,

      1986, pp 519-618

 

2.   Kandakoudi F, Drossou V, Tzimouli V, et al: Serum concentrations of 10

      acute-phase proteins in healthy term and preterm infants from birth to

      age 6 months. Clin Chem 1995;41:605-608

 

3.   Behring Nephelometer II Operations Instruction Manual. Dade

      Behring, Inc., Newark, DE

 

Key