beta2-Microglobulin, Blood and Urine


β2-Microglobulin, Blood and Urine

Synonym/acronym: β2-M, BMG.

Common use

To assist in diagnosing malignancy such as lymphoma, leukemia, or multiple myeloma. Also valuable in assessing for chronic severe inflammatory and renal diseases.

Specimen

Serum (1 mL) collected in a red- or red/gray-top tube or 5 mL urine from a timed collection in a clean plastic container with 1 N NaOH as a preservative.

Normal findings

(Method: Immunochemiluminometric assay)
SampleConventional & SI Units
Serum
 Newborn–1 mo1.6–4.8 mg/L
 2–6 mo1–3.8 mg/L
 7–11 mo0.9–3.1 mg/L
 1–6 yr0.6–2.4 mg/L
 7–18 yr0.7–2 mg/L
 Adult0.6–2.4 mg/L
Urine0–300 mcg/L

Description

β2-Microglobulin (BMG) is a protein component of human leukocyte antigen (HLA) complexes. BMG is on the surface of most cells and is therefore a useful indicator of cell death or unusually high levels of cell production. BMG is a small protein and is readily reabsorbed by kidneys with normal function. BMG increases in inflammatory conditions and when lymphocyte turnover increases, such as in lymphocytic leukemia or when T-lymphocyte helper (OKT4) cells are attacked by HIV. Serum BMG becomes elevated with malfunctioning glomeruli but decreases with malfunctioning tubules because it is metabolized by the renal tubules. Conversely, urine BMG decreases with malfunctioning glomeruli but becomes elevated with malfunctioning tubules.

This procedure is contraindicated for

    N/A

Indications

  • Detect aminoglycoside toxicity
  • Detect chronic lymphocytic leukemia, multiple myeloma, lung cancer, hepatoma, or breast cancer
  • Detect HIV infection (Note: levels do not correlate with stages of infection)
  • Evaluate renal disease to differentiate glomerular from tubular dysfunction
  • Evaluate renal transplant viability and predict rejection
  • Monitor antiretroviral therapy

Potential diagnosis

Increased in

  • AIDS (related to increased lymphocyte turnover)
  • Aminoglycoside toxicity (related to renal damage; urine BMG becomes elevated before creatinine)
  • Amyloidosis (related to chronic inflammatory conditions associated with increased BMG and other acute-phase reactant proteins; also related to deposition of amyloid in joints and tissues of patients receiving long-term hemodialysis)
  • Autoimmune disorders (related to increased lymphocyte turnover)
  • Breast cancer (related to increased lymphocyte turnover; serum BMG indicates tumor growth rate, size, and response to treatment)
  • Crohn’s disease (related to chronic inflammatory conditions associated with increased BMG and other acute-phase reactant proteins)
  • Felty’s syndrome (related to chronic inflammatory conditions associated with increased BMG and other acute-phase reactant proteins)
  • Heavy metal poisoning
  • Hepatitis (related to increased lymphocyte turnover in response to viral infection)
  • Hepatoma (related to increased lymphocyte turnover; serum BMG indicates tumor growth rate, size, and response to treatment)
  • Hyperthyroidism (related to increased lymphocyte turnover in immune thyroid disease)
  • Leukemia (chronic lymphocytic) (related to increased lymphocyte turnover; serum BMG indicates tumor growth rate, size, and response to treatment)
  • Lung cancer (related to increased lymphocyte turnover; serum BMG indicates tumor growth rate, size, and response to treatment)
  • Lymphoma (related to increased lymphocyte turnover; serum BMG indicates tumor growth rate, size, and response to treatment)
  • Multiple myeloma (related to increased lymphocyte turnover)
  • Poisoning with heavy metals, such as mercury or cadmium (related to renal damage that decreases BMG absorption)
  • Renal dialysis (related to ability of renal tubule to reabsorb BMG)
  • Renal disease (glomerular): serum only (related to ability of renal tubule to reabsorb BMG)
  • Renal disease (tubular): urine only (related to ability of renal tubule to reabsorb BMG)
  • Sarcoidosis
  • Sjögren’s disease
  • Systemic lupus erythematosus (related to chronic inflammatory conditions associated with increased BMG and other acute-phase reactant proteins)
  • Vasculitis (related to chronic inflammatory conditions associated with increased BMG and other acute-phase reactant proteins)
  • Viral infections (e.g., cytomegalovirus) (related to increased lymphocyte turnover)

Decreased in

    Renal disease (glomerular): urine only Renal disease (tubular): serum only Response to zidovudine (AZT) (related to decreased viral replication and lymphocyte destruction)

Critical findings

    N/A

Interfering factors

  • Drugs and proteins that may increase serum BMG levels include cyclosporin A, gentamicin, interferon alfa, and lithium.
  • Drugs that may decrease serum BMG levels include zidovudine.
  • Drugs that may increase urine BMG levels include azathioprine, cisplatin, cyclosporin A, furosemide, gentamicin, iodixanol, iopentol, mannitol, nifedipine, sisomicin, and tobramycin.
  • Urinary BMG is unstable at pH less than 5.5.

Nursing Implications and Procedure

Potential nursing problems

ProblemSigns & SymptomsInterventions
Fatigue (Related to metastatic disease; tumor; pain; radiation therapy; chemotherapy; anemia; insufficient nutrition; anxiety) Report of tiredness; inability to maintain activities of daily living at current level; inability to restore energy after rest or sleep Discuss the implementation of energy conservation activities (even pace when working, frequent rest periods, frequent items in easy reach, push items instead of pulling); limit naps to increase nighttime sleeping; set priorities for energy expenditures; order transfusion of ordered blood or blood products to treat anemia; administer ordered psychostimulants as appropriate; encourage participation in ordered psychotherapy
Spirituality (Related to diagnosis of terminal illness; active dying; ongoing chronic illness; anxiety; fear; hopelessness)Disharmony between personal beliefs, value system, and threat to life; anger; lack of courage; no purpose or meaning to life; lack of acceptance of diagnosis, disease process; separation from support system; disinterest in connecting with others Assess for the presence of religious affiliation; assess cultural factors that influence spirituality; encourage verbalization of feelings; work proactively to develop a positive relationship with the patient; assist decision-making working within patient’s value system; facilitate interaction with religious leaders; support faith-based rituals
Infection (Related to altered immune response associated with chemotherapy and radiation therapy; opportunistic hosts)Fever; evidence of local or systemic infection; blood cultures positive for infection; sputum culture positive for infection; increased heart rate and respiratory rate; chills; change in mental status; fatigue; malaise; weakness; anorexia; headache; nausea; elevated blood glucose; hypotension; diminished oxygen saturation; elevated WBC; elevated C-reactive protein Provide standard precautions in the provision of care; correlate symptoms with laboratory values and disease process; trend vital signs and laboratory values to monitor for improvement; administer prescribed antibiotics and medications for fever reduction; administer cooling measures; be vigilant with hand hygiene; educate patient and family regarding good hand hygiene; infuse ordered IV fluids to support adequate hydration; ensure implementation of infection prevention measures with consideration of age and culture such as adequate nutrition; perform aseptic wound care; ensure skin care; ensure oral care; ensure adequate rest; avoid exposure to opportunistic hosts; send cultures to the laboratory as ordered; correlate culture findings with selected antibiotics; avoid mouthwashes with high alcohol content; notify health-care provider (HCP) of temperature spikes or flu-like symptoms; discuss implementation of protective isolation for neutrophil count less than 500 to 1,000 × 103/microL
Bleeding (Related to altered bone marrow function secondary to radiation therapy and chemotherapy)Decreased platelet count; altered level of consciousness; hypotension; increased heart rate; decreased HGB and HCT; capillary refill greater than three seconds; cool extremities Administer prescribed platelets or blood as ordered; monitor and trend platelet count; increase frequency of vital sign assessment with variances in results; monitor for vital sign trends; administer stool softeners as needed; monitor stool for blood; encourage intake of foods rich in vitamin K; monitor and trend HGB/HCT; assess skin for petechiae, purpura, hematoma; monitor for blood in emesis or sputum; institute bleeding precautions (prevent unnecessary venipuncture; avoid IM injections; prevent trauma; be gentle with oral care, suctioning; avoid use of a sharp razor); coordinate lab draws to decrease number of sticks; review transfusion reaction symptoms

Pretest

  • Positively identify the patient using at least two unique identifiers before providing care, treatment, or services.
  • Patient Teaching: Inform the patient that the test is used to evaluate renal disease, AIDS, and certain malignancies.
  • 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 genitourinary and immune systems, symptoms, and results of previously performed laboratory tests and diagnostic and surgical procedures.
  • Note any recent procedures that can interfere with test results.
  • Obtain a list of the patient’s current medications, including herbs, nutritional supplements, and nutraceuticals (see Effects of Natural Products on Laboratory Values online at DavisPlus).
  • Sensitivity to social and cultural issues, as well as concern for modesty, are important in providing psychological support before, during, and after the procedure.
  • Note that there are no food, fluid, or medication restrictions unless by medical direction.

    • Blood

  • Review the procedure with the patient. 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.

    • Urine

  • Review the procedure with the patient. Provide a nonmetallic urinal, bedpan, or toilet-mounted collection device.
  • Usually, a 24-hr urine collection is ordered. Inform the patient that all urine over a 24-hr period must be saved; instruct the patient to avoid defecating in the collection device and to keep toilet tissue out of the collection device to prevent contamination of the specimen. Place a sign in the bathroom as a reminder to save all urine.
  • Instruct the patient to void all urine into the collection device and then pour the urine into the laboratory collection container. Alternatively, the specimen can be left in the collection device for a health-care staff member to add to the laboratory collection container.

Intratest

  • Potential complications: N/A
  • Instruct the patient to cooperate fully and to follow directions. Direct the patient to breathe normally and to avoid unnecessary movement during the venipuncture.
  • 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 as appropriate.

    • Blood

  • Avoid the use of equipment containing latex if the patient has a history of allergic reaction to latex.
  • 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.

    • Urine

  • Obtain a clean 3-L urine specimen container, toilet-mounted collection device, and plastic bag (for transport of the specimen container). The specimen must be refrigerated or kept on ice throughout the entire collection period. If an indwelling urinary catheter is in place, the drainage bag must be kept on ice.
  • If possible, begin the test between 6 and 8 a.m. Collect first voiding and discard. Record the time the specimen was discarded as the beginning of the timed collection period. At the same time the next morning, ask the patient to void and add this last voiding to the container. Urinary output should be recorded throughout the collection time.
  • If an indwelling catheter is in place, replace the tubing and container system at the start of the collection time. Keep the container system on ice during the collection period, or empty the urine into a larger container periodically during the collection period; monitor to ensure continued drainage, and conclude the test the next morning at the same hour the collection started.
  • Compare the quantity of urine with the urinary output record for the collection at the conclusion of the test. If the specimen contains less than what was recorded as output, some urine may have been discarded, thus invalidating the test.

    • Blood or Urine

  • Promptly transport the specimen to the laboratory for processing and analysis. Include on the urine specimen label the amount of urine and ingestion of any medications that can affect test results.

Post-Test

  • Inform the patient that a report of the results will be made available to the requesting HCP, who will discuss the results with the patient.
  • Nutritional Considerations: Stress the importance of good nutrition, and suggest that the patient meet with a nutritional specialist. Also, stress the importance of following the care plan for medications and follow-up visits.
  • Social and Cultural Considerations: Recognize anxiety related to test results, and be supportive of impaired activity related to weakness, perceived loss of independence, and fear of shortened life expectancy. Discuss the implications of abnormal test results on the patient’s lifestyle. Provide teaching and information regarding the clinical implications of the test results, as appropriate. Educate the patient regarding access to counseling services. Provide contact information, if desired, for AIDS information provided by the National Institutes of Health (www.aidsinfo.nih.gov).
  • Social and Cultural Considerations: Counsel the patient, as appropriate, regarding risk of transmission and proper prophylaxis, and reinforce the importance of strict adherence to the treatment regimen.
  • Social and Cultural Considerations: Offer support, as appropriate, to patients who may be the victims of rape or sexual assault.
  • 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.

  • Patient Education

    • Educate the patient regarding the risk of infection related to immunosuppressed inflammatory response and fatigue related to decreased energy production.
    • Educate the patient regarding access to counseling services.
    • Provide a nonjudgmental, nonthreatening atmosphere for a discussion during which risks of sexually transmitted diseases are explained.
    • Discuss emotional problems the patient may experience (e.g., guilt, depression, anger).
    • Reinforce information given by the patient’s HCP regarding further testing, treatment, or referral to another HCP.
    • Inform the patient that retesting may be necessary.
    • Answer any questions or address any concerns voiced by the patient or family.

  • Expected Patient Outcomes

    • Knowledge
    • States understanding of the normal range of a platelet count
    • States understanding of the rationale for bleeding precautions to overall health
    • Skills
    • Demonstrates proficient use of nasal spray and lip lubricant to decrease cracking and bleeding
    • Demonstrates proficiency in protecting self from injury and trauma with associated bleeding risk
    • Attitude
    • Complies with the request for type and cross match for possible platelet transfusion
    • Complies with recommendation to attend support groups to assist with managing end-of-life concerns

Related Monographs

  • Related tests include antimicrobial drugs, ANA, barium enema, biopsy (bone marrow, biopsy breast, biopsy liver, biopsy lung, biopsy lymph node), BUN, capsule endoscopy, CD4/CD8 enumeration, colonoscopy, CRP, cancer antigens, CBC, creatinine, cultures (mycobacteria, sputum, viral), cytology sputum, CMV, ESR, gallium scan, GGT, hepatitis antigens and antibodies (A, B, C), HIV-1/HIV-2 serology, immunofixation electrophoresis, immunoglobulins (A, G, and M), liver and spleen scan, lymphangiogram, MRI breast, mammogram, microalbumin, osmolality, protein total and fractions, renogram, RF, stereotactic breast biopsy, TB tests, US (breast, liver, lymph node), and UA.
  • Refer to the Genitourinary and Immune systems tables at the end of the book for related tests by body system.