Beta2 Microglobulin - Serum (T048) [Back]
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| RISK ASSESSMENT VALUE: |
Beta2-microglobulin (b2M) is a single-chain polypeptide (mw=11,800) structurally similar to the CH3 domain of the immunoglobulin molecule. b2M forms the light chain portion of Class I HLA antigens, and therefore is found on the surface of all nucleated cells. Cell membrane turnover is the main source of serum b2M, which passes from the circulation through glomerular filtration. Much of the b2M in the filtrate is reabsorbed in the proximal renal tubules; the remaining fraction is excreted in the urine.
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| NORMAL RESULTS: |
Serum: less than 2.4 mg/L
Random urine: nonreactive
Saliva: nonreactive
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| ABNORMAL RESULTS: |
Increased values with renal, chronic lymphocytic leukemia, activity of AIDS, Crohns disease, hepatitis, sarcoidosis, vasculitis, and some malignancies.
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| ADDITIONAL TESTS: |
None
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| SAMPLE NEEDED: |
Separated serum from red-stopper tube, random urine or saliva collection
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| SAMPLE STABILITY: |
Stable when refrigerated, for 48 hours, indefinitely, when frozen. Avoid freezing and thawing.
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| METHOD & INSTRUMENT: |
Microparticle enzyme immunoassay, Roche 917.
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| INTERFERING FACTORS: |
Specimens from individuals who have received preparations of mouse monoclonal antibodies for diagnosis or therapy may contain human anti-mouse antibodies. Such specimens may show either falsely elevated or depressed values when tested with assays kits which employ mouse monoclonal antibodies.
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| PURPOSE: |
Elevated serum levels of b2M are found in patients with renal disease involving reduced glomerular filtration rate, autoimmune diseases, chronic inflammatory diseases, lymphoproliferative disorders and other malignant diseases. Measurement of b2M is useful in the evaluation of glomerular filtration, especially after renal transplantation. Serum b2M levels rise with impaired renal function. By contrast, a drop in the serum b2M level indicates a viable renal graft and a good prognosis. Elevated urine and serum values of b2M may indicate severe renal tubular damage resulting from acute rejection of a renal transplant. Elevated urine B2M levels may also occur because of renal tubular damage caused by exposure to heavy metals, chemotherapy or treatment with anti-inflammatory drugs. Similarly, elevated urine b2M levels may help in the differentiation between upper and lower urinary tract infections; patients with renal infections (chronic pyelonephritis) often have elevated urinary b2M levels, whereas patients with cystitis typically do not. In chronic inflammatory diseases such as rheumatoid arthritis, Sjogrens syndrome, systemic lupus erythematosus, sarcoidosis and cirrhosis, serum b2M levels often are increased as a result of inflammatory cell proliferation and turnover. Patients with infectious mononucleosis, as well as patient with lymphoid malignancies such as multiple myeloma, chronic lymphocytic leukemia, and non-Hodgkin's lymphomas commonly exhibit commonly exhibit elevated serum b2M levels. Likewise, recent reports indicated that patients with acquired immunodeficiency syndrome (AIDS) or with AIDS related complex (ARC) often have high levels of serum b2M. Based on the observed b2M elevations in affected individuals, serum b2M has been proposed as a market for disease activity in AIDS.
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| PROFILE INCLUDES: |
1019
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| RISK RANGE & UNITS: |
Serum 0-2.4 mg/L
Random urine: Non-reactive
Saliva: Non-reactive
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