Cold Agglutinin Titer

Cold Agglutinin Titer

Synonym/acronym: Mycoplasma serology.

Common use

To identify and confirm the presence of viral infections such as found in atypical pneumonia.

Specimen

Serum (2 mL) collected in a red-top tube. The tube must be placed in a water bath or heat block at 37°C for 1 hr and allowed to clot before the serum is separated from the red blood cells (RBCs).

Normal findings

(Method: Patient serum containing autoantibodies titered against type O RBCs at 2°C to 8°C. Type O cells are used because they have no antigens on the cell membrane surface. Agglutination with patient sera would not occur because of reaction between RBC blood type antigens and patient blood type antibodies.) Negative: Single titer less than 1:32 or less than a fourfold increase in titer over serial samples. High titers may appear spontaneously in elderly patients and persist for many years.

Description

Cold agglutinins are antibodies that cause clumping or agglutination of RBCs at cold temperatures in individuals with certain conditions or who are infected by particular organisms. Cold agglutinins are associated with Mycoplasma pneumoniae infection. M. pneumoniae has i antigen specificity to human RBC membranes. Fetal cells largely contain i antigens, but by 18 mo most cells carry the I antigen. The agglutinins are usually immunoglobulin M (IgM) antibodies and cause agglutination of cells at temperatures in the range of 0°C to 10°C. The temperature of circulating blood in the extremities may be lower than core temperatures. RBCs of affected individuals may agglutinate and obstruct blood vessels in fingers, toes, and ears, or they may initiate the complement cascade. Affected cells may be lysed immediately within the capillaries and blood vessels as a result of the action of complement on the cell wall, or they may return to the circulatory system and be lysed in the spleen by macrophages.

The titer endpoint is the highest dilution of serum that shows a specific antigen-antibody reaction. Single titers greater than 1:64, or a fourfold increase in titer between specimens collected 5 or more days apart, are clinically significant. Patients affected with primary atypical viral pneumonia exhibit a rise in titer 8 to 10 days after the onset of illness. IgM antibodies peak in 12 to 25 days and begin to diminish 30 days after onset.

This procedure is contraindicated for

    N/A

Indications

  • Assist in the confirmation of primary atypical pneumonia, influenza, or pulmonary embolus
  • Provide additional diagnostic support for cold agglutinin disease associated with viral infections or lymphoreticular cancers

Potential diagnosis

Increased in

  • Mycoplasma infection stimulates production of antibodies against specific RBC antigens in affected individuals

  • Cirrhosis
  • Gangrene
  • Hemolytic anemia
  • Infectious diseases (e.g., staphylococcemia, influenza, tuberculosis)
  • Infectious mononucleosis
  • Malaria
  • M. pneumoniae (primary atypical pneumonia)
  • Multiple myeloma
  • Pulmonary embolism
  • Raynaud’s disease (severe)
  • Systemic lupus erythematosus
  • Trypanosomiasis

Decreased in

    N/A

Critical findings

    N/A

Interfering factors

  • Antibiotic use may interfere with or decrease antibody production.
  • A high antibody titer may interfere with blood typing and crossmatching procedures.
  • High titers may appear spontaneously in elderly patients and persist for many years.
  • Prompt and proper specimen processing, storage, and analysis are important to achieve accurate results. Specimens should always be transported to the laboratory as quickly as possible after collection. The specimen must clot in a 37°C water bath for 1 hr before separation. Refrigeration of the sample before serum separates from the RBCs may falsely decrease the titer.

Nursing Implications and Procedure

Pretest

  • Positively identify the patient using at least two unique identifiers before providing care, treatment, or services.
  • Patient Teaching:   Inform the patient this test can assist in diagnosing primary atypical pneumonia versus other infectious diseases or immune-related conditions. Explain that the test detects antibodies developed during an infection that attack their RBCs when their body is exposed to cold temperatures.
  • Obtain a history of the patient’s complaints, including a list of known allergens, especially allergies or sensitivities to latex.
  • Obtain a history of the patient’s immune and respiratory systems, as well as results of previously performed laboratory tests and diagnostic and surgical procedures.
  • Obtain a list of the patient’s current medications, including herbs, nutritional supplements, and nutraceuticals (see Effects of Natural Products on Laboratory Values).
  • Note any recent medications that can interfere with test results.
  • Review the procedure with the patient. Inform the patient that multiple specimens may be required. Inform the patient that specimen collection takes approximately 5 to 10 min. Address concerns about pain and explain that there may be some discomfort during the venipuncture.
  • Sensitivity to social and cultural issues,  as well as concern for modesty, is important in providing psychological support before, during, and after the procedure.
  • Note that there are no food, fluid, or medication restrictions (except antibiotics) unless by medical direction.

Intratest

  • Potential complications: N/A
  • Ensure that the patient has complied with medication restrictions prior to the procedure.
  • Avoid the use of equipment containing latex if the patient has a history of allergic reaction to latex.
  • Instruct the patient to cooperate fully and to follow directions. Direct the patient to breathe normally and to avoid unnecessary movement.
  • Observe standard precautions, and follow the general guidelines in Patient Preparation and Specimen Collection. Positively identify the patient, and label the appropriate specimen container with the corresponding patient demographics, initials of the person collecting the specimen, date, and time of collection. Perform a venipuncture.
  • Remove the needle and apply direct pressure with dry gauze to stop bleeding. Observe/assess venipuncture site for bleeding or hematoma formation and secure gauze with adhesive bandage.
  • Promptly transport the specimen to the laboratory for processing and analysis.
  • Inform the laboratory if the patient is receiving antibiotics.

Post-Test

  • Inform the patient that a report of the results will be made available to the requesting health-care provider (HCP), who will discuss the results with the patient.
  • Instruct the patient to resume antibiotics as directed by the HCP. Instruct the patient in the importance of completing the entire course of antibiotic therapy even if no symptoms are present.
  • Reinforce information given by the patient’s HCP regarding further testing, treatment, or referral to another HCP. Emphasize the need for the patient to return in 7 to 14 days for a convalescent blood sample. Answer any questions or address any concerns voiced by the patient or family.
  • Depending on the results of this procedure, additional testing may be performed to evaluate or monitor progression of the disease process and determine the need for a change in therapy. Evaluate test results in relation to the patient’s symptoms and other tests performed.

Related Monographs

  • Related tests include arterial/alveolar oxygen ratio, blood gases, chest x-ray, CBC, CBC WBC count, Coombs’ antiglobulin, culture viral, ESR, gallium scan, infectious mononucleosis screen, lung perfusion scan, plethysmography, and pleural fluid analysis.
  • Refer to the Immune and Respiratory systems tables at the end of the book for related tests by body system.
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References in periodicals archive ?
3][micro]l), lactate dehydrogenase (LDH 760 IU/L) and cold agglutinin titer of 1:128.