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HelpTest Code B2MU Beta-2 Microglobulin, Random, Urine
Reporting Name
Beta-2 Microglobulin, UUseful For
Evaluation of renal tubular damage
Monitoring exposure to cadmium and mercury
Method Name
Automated Chemiluminescent Immunometric Assay
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
UrineSpecimen 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.
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 |
Reference Values
≤300 mcg/L
Day(s) Performed
Monday, Wednesday, Friday
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 |
Secondary ID
602026Clinical 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.
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.
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.
Clinical Reference
1. Ikeda M, Ezaki T, Tsukahara T, et al. Threshold levels of urinary cadmium in relation to increases in urinary beta2-microglobulin among general Japanese populations. Toxicol Lett. 2003;137(3):135-141
2. Moriguchi J, Ezaki T, Tsukahara T, et al. Comparative evaluation of four urinary tubular dysfunction markers, with special references to the effects of aging and correction for creatinine concentration. Toxicol Lett. 2003;143(3):279-290
3. Stefanovic V, Cukuranovic R, Mitic-Zlatkovic M, Hall PW. Increased urinary albumin excretion in children from families with Balkan nephropathy. Pediatr Nephrol. 2002;17(11):913-916
4. Assounga AG. Beta 2 microglobulin in kidney failure: A review and an algorithm for renal replacement therapy. Saudi J Kidney Dis Transpl. 2021;32(5):1214-1220. doi:10.4103/1319-2442.344740
5. Khanijou V, Zafari N, Coughlan MT, MacIsaac RJ, Ekinci EI. Review of potential biomarkers of inflammation and kidney injury in diabetic kidney disease. Diabetes Metab Res Rev. 2022;38(6):e3556. doi:10.1002/dmrr.3556
Method Description
Testing is performed on the Immulite 2000. The Immulite 2000 Beta-2 Microglobulin assay is a solid phase, 2-site chemiluminescent enzyme-labeled immunometric assay. The solid-phase bead is coated with an affinity-purified murine monoclonal anti-beta-2 antibody. The serum sample and alkaline phosphatase conjugated affinity-purified goat polyclonal anti-beta-2 antibody are incubated to bind beta-2 microglobulin into an antibody sandwich complex.
The chemiluminescent substrate, a phosphate ester of adamantyl dioxetane, in the presence of alkaline phosphatase produces light proportional to the concentration of the beta-2 microglobulin in the sample.(Package insert: IMMULITE 2000 Beta-2 Microglobulin. Siemens Healthcare Diagnostics; 03/15/2018)
Report Available
1 to 3 daysSpecimen Retention Time
2 weeksTest Classification
This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.Forms
If not ordering electronically, complete, print, and send a Renal Diagnostics Test Request (T830) with the specimen.