Beta-2 Microglobulin, Random, Urine

Test Code

B2URN

Alias/See Also

Epic: LAB3709
Mayo: B2MU

CPT Codes
82232

Preferred Specimen

Specimen Type: Urine
Collection Container: Sterile container
Specimen Volume: 3 mL

Patient Preparation
For 12 hours before specimen collection, do not take multivitamins or dietary supplements containing biotin (vitamin B7) which is commonly found in hair, skin, and nail supplements and multivitamins.

Minimum Volume

1 mL

Instructions

Patient should empty bladder.
Have patient drink at least 0.5 liters of water.
Within 1 hour, collect a random urine specimen.
Add 1 M sodium hydroxide (NaOH) as preservative to the collection. This preservative is intended to achieve an approximate pH of between 6 and 8.

Transport Container

Plastic vial

Specimen Stability

Specimen Type	Temperature	Time	Special Container
Urine	Frozen (preferred)	14 days
	Refrigerated	48 hours

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)

Specimen with pH <6

Methodology
Automated Chemiluminescent Immunometric Assay

Setup Schedule

Monday, Wednesday, Friday

Report Available

1 to 3 days

Limitations

CAUTIONS

Degradation of beta-2 microglobulin occurs at pH less than 6.0. At the time of urine collection, 1M NaOH needs to be added as preservative to achieve a pH between 6 and 8.

For diagnostic purposes, the results obtained from this assay should always be used in combination with the clinical examination, patient medical history, and other findings.

Reference Range

REFERENCE VALUES

< or =300 mcg/L

INTERPRETATION

Increased excretion is consistent with renal tubular damage.

Beta-2 microglobulin excretion is increased 100 to 1000 times the upper limit of the reference interval in cadmium-exposed workers.

Clinical Significance

USEFUL FOR

Evaluation of renal tubular damage

Monitoring exposure to cadmium and mercury

CLINICAL INFORMATION

Beta-2 microglobulin is a low-molecular-weight protein that forms the light chain component of class I histocompatibility (HLA: human leukocyte antigen) antigens. Because of its low molecular weight (11,800 daltons), 95% of free beta-2 microglobulin is rapidly eliminated by glomerular filtration. Proximal tubular cells then take up 99.9% of this filtered amount by endocytosis, after which degradation to amino acids occurs. Normal urinary excretion of beta-2 microglobulin is less than 370 micrograms per 24 hours; higher rates are interpreted as evidence of tubular dysfunction.

Increased urine levels are seen in proximal tubular renal damage due to a variety of causes including Wilson disease, Fanconi syndrome, untreated congenital galactosemia, nephrocalcinosis, cystinosis, chronic potassium depletion, interstitial nephritis, connective-tissue diseases such as rheumatoid arthritis and Sjogren syndrome. Occupational exposure to heavy metals such as cadmium and mercury could also lead to increase levels of beta-2 microglobulin in urine.

Performing Laboratory
Mayo Clinic Laboratories - Rochester
3050 Superior Drive NW
Rochester, MN 55901

Additional Information
Beta-2 Microglobulin, Random, Urine

Last Updated: September 5, 2023
Last Review: N. Wolford, September 5, 2023

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.