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Test Code B2MU Beta-2 Microglobulin, Random, Urine


Specimen Required


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.

Supplies: Sarstedt Aliquot Tube, 5 mL (T914)

Container/Tube: Plastic, urine tube

Specimen Volume: 1.0 mL

Collection Instructions:

1. Patient should empty bladder.

2. Have patient drink at least 0.5 liters of water.

3. Within 1 hour, collect a random urine specimen.

4. 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.


Secondary ID

602026

Useful For

Evaluation of renal tubular damage

 

Monitoring exposure to cadmium and mercury

Method Name

Automated Chemiluminescent Immunometric Assay

Reporting Name

Beta-2 Microglobulin, U

Specimen Type

Urine

Specimen Minimum Volume

0.5mL

Specimen Stability Information

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

Reject Due To

Specimen with pH <6 Reject

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.

Reference Values

≤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.

CPT Code Information

82232

LOINC Code Information

Test ID Test Order Name Order LOINC Value
B2MU Beta-2 Microglobulin, U 1953-9

 

Result ID Test Result Name Result LOINC Value
B2MU Beta-2 Microglobulin, U 1953-9

Forms

If not ordering electronically, complete, print, and send a Renal Diagnostics Test Request (T830) with the specimen.