Beta-2-Microglobulin, Random Urine (UBETA)

Patient should void bladder, then drink at least 500 mL of water.

Test Code

Quest Code

Alias/See Also

CPT Codes

CPT code 81050 may be added at an additional charge for volume measurement

Preferred Specimen

10 mL random urine collected in a plastic, leak-proof container

Patient Preparation

Patient should void bladder, then drink at least 500 mL of water

Minimum Volume
10 mL

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 (#179979 available through Client Supply).
4. Ship refrigerated.
5. Alternatively, if the collection tubes are not available, pH the specimen 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 Container
Plastic screw-cap vial
Kennestone nursing: call lab for instructions regarding collection and transport.

Transport Temperature
Refrigerated (cold packs)

Specimen Stability
Room temperature: 72 hours
Refrigerated: 7 days
Frozen: 21 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 • Any specimen with pH less than 6


Report Available
2 days

Reference Range
<18 Years Not established
Adults ≤0.23 mg/L

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.

Performing Laboratory
Quest Diagnostics Nichols Institute-Chantilly VA
14225 Newbrook Drive
Chantilly, VA 20151-2228

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.