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Beta-2-Microglobulin, Urine
Test Code4944
CPT Codes
82232
Includes
CPT code 81050 may be added at an additional charge for volume measurement
Preferred Specimen
10 mL random urine collected in a Quest Diagnostics Beta-2 Microglobulin Transport Tube (available through client supply)
Patient Preparation
Patient should void bladder, then drink at least 500 mL (approximately 17 oz) of water
Minimum Volume
10 mL
Instructions
1. Patient should void bladder, then drink at least 500 mL (approximately 17 oz) of water.
2. A urine sample should be collected within 1 hour.
3. Pour exactly 10 mL of random urine into a Quest Diagnostics Beta-2 Microglobulin Transport Tube (available through Client Supply).
4. Ship room temperature.
5. Alternatively, if the collection tubes are not available, pH the specimen must be adjusted to between 6 and 8 using 1N NaOH prior to shipping.
2. A urine sample should be collected within 1 hour.
3. Pour exactly 10 mL of random urine into a Quest Diagnostics Beta-2 Microglobulin Transport Tube (available through Client Supply).
4. Ship room temperature.
5. Alternatively, if the collection tubes are not available, pH the specimen must be adjusted to between 6 and 8 using 1N NaOH prior to shipping.
Beta-2 Microglobulin in urine is unstable in acidic urine (less than pH 6). Exactly 10 mL of urine in the Quest Diagnostics Beta-2 Microglobulin Transport Tube is required to achieve the required pH of between 6 and 8. Any volume above or below 10 mL will result in a pH that is outside the acceptable range.
Transport Temperature
Room temperature
Specimen Stability
Room temperature: 5 days
Refrigerated: 15 days
Frozen: 30 days
Refrigerated: 15 days
Frozen: 30 days
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Specimens received in a non-Beta-2 Microglobulin transport tube with a pH less than 6 • Any volume other than 10 mL urine in the transport tube • Specimens received past stability • Any specimen with pH less than 6.0
Methodology
Immunoturbidimetric
Setup Schedule
Set up: Mon-Sat; Report available: 3 days
Clinical Significance
Beta-2-Microglobulin (B2M) is a low molecular weight protein that forms the light chain component of the histocompatibility antigen. It is synthesized by all nucleated cell types. It is an integral part of the class I MHC antigens and is present in all body fluids. B2M is filtered through the glomeruli of the kidney and is then reabsorbed and catabolised by the proximal tubular cells. In normal patients only trace amounts of B2M appear in the urine. Elevated urine B2M is seen in tubulo-interstitial disorders. Increased urine B2M is seen in cadmium exposure, diatrizoate, exercise, fever, nephrectomy, semen. There is evidence that monitoring B2M levels in HIV-infected individuals offers an independent predictor of progression to AIDS, leukemia and lymphoma.
