Haptoglobin

Synonym/Acronym

hapto, HP, Hp.

Rationale

To assist in evaluating for intravascular hemolysis related to transfusion reactions, chronic liver disease, hemolytic anemias, and tissue inflammation or destruction.

Patient Preparation

There are no food, fluid, activity, or medication restrictions unless by medical direction.

Normal Findings

Method: Immunoturbidimetric.

Conventional Units		SI Units (Conventional Units × 0.01)
30–200 mg/dL		0.3–2 g/L

Critical Findings and Potential Interventions ⬆ ⬇

Overview ⬆ ⬇

(Study type: Blood collected in a gold-, red-, or red/gray-top tube; related body system: Circulatory/hematopoietic and digestive systems.)

Haptoglobin is an alpha₂-globulin produced in the liver. It binds with the free hemoglobin released when red blood cells (RBCs) are lysed. The complexed (bound) hemoglobin is then removed from circulation by the spleen. Haptoglobin is used as a marker for intravascular hemolysis because the amount of free hemoglobin from a significant number of lysed RBCs will exceed the amount of haptoglobin normally available for binding. In conditions such as hemolytic anemia (e.g., drug induced, inherited, acute transfusion reaction), the liver is unable to compensate, so consumption exceeds production, and haptoglobin levels are decreased.

Indications ⬆ ⬇

Assist in the investigation of suspected transfusion reaction.
Evaluate known or suspected chronic liver disease, as indicated by decreased levels of haptoglobin.
Evaluate known or suspected disorders characterized by excessive RBC hemolysis, as indicated by decreased levels of haptoglobin.
Evaluate known or suspected disorders involving a diffuse inflammatory process or tissue destruction, as indicated by elevated levels of haptoglobin.

Interfering Factors ⬆ ⬇

Drugs and other substances that may increase haptoglobin levels include anabolic steroids and danazol.
Drugs and other substances that may decrease haptoglobin levels include aminosalicylic acid, chlorpromazine, dapsone, dextran, diphenhydramine, furazolidone, isoniazid, nitrofurantoin, norethindrone, oral contraceptives, quinidine, resorcinol, stibophen, tamoxifen, and tripelennamine.

Potential Medical Diagnosis: Clinical Significance of Results ⬆ ⬇

Increased In

Haptoglobin is an acute-phase reactant protein, and any condition that stimulates an acute-phase response will result in elevations of haptoglobin.

Biliary obstruction
Disorders involving tissue destruction, such as cancers, burns, and acute myocardial infarction
Infection or inflammatory diseases, such as ulcerative colitis, arthritis, and pyelonephritis
Tumors
Steroid therapy

Decreased In

Autoimmune hemolysis (related to increased excretion rate of haptoglobin bound to free hemoglobin; rate of excretion exceeds the liver’s immediate ability to replenish)
Hemolysis due to drug reaction (related to increased excretion rate of haptoglobin bound to free hemoglobin; rate of excretion exceeds the liver’s immediate ability to replenish)
Hemolysis due to mechanical destruction (e.g., artificial heart valves, contact sports, subacute bacterial endocarditis) (related to increased excretion rate of haptoglobin bound to free hemoglobin; rate of excretion exceeds the liver’s immediate ability to replenish)
Hemolysis due to RBC membrane or metabolic defects (related to increased excretion rate of haptoglobin bound to free hemoglobin; rate of excretion exceeds the liver’s immediate ability to replenish)
Hemolysis due to transfusion reaction (related to increased excretion rate of haptoglobin bound to free hemoglobin; rate of excretion exceeds the liver’s immediate ability to replenish)
Hypersplenism (related to increased excretion rate of haptoglobin bound to free hemoglobin due to increased RBC destruction; rate of excretion exceeds the liver’s immediate ability to replenish)
Ineffective hematopoiesis due to conditions such as folate deficiency or hemoglobinopathies (related to decreased numbers of RBCs or dysfunctional binding in the presence of abnormal hemoglobins)
Liver disease (related to decreased production)
Pregnancy (related to effect of estrogen)

Nursing Implications ⬆

Before the Study: Planning and Implementation

Teaching the Patient What to Expect

Explain that a blood sample is needed for the test.
Discuss how this test can assist with evaluating causes of RBC loss.

After the Study: Implementation & Evaluation Potential Nursing Actions

Avoiding Complications

Explain the importance of immediately reporting symptoms of a transfusion reaction, including chills, fever, flushing, back pain, or rapid heartbeat to the health-care provider.

Treatment Considerations

Interventions/actions include the following: Discuss how RBC loss can contribute to anemia and associated problems. Monitor closely for fatigue, changing oxygenation, altered level of consciousness, confusion, and fall and injury risk associated with these issues.

Clinical Judgement

Consider how to approach future transfusion concerns associated with current transfusion reaction.

Follow-Up Evaluation and Desired Outcomes

Understands that additional testing may be necessary to quickly evaluate, monitor, and treat a suspected transfusion reaction.