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Specimen Type: Urine (protease inhibitor coctail recommended - contact PBI for further info)
Optimum Volume: 0.5 mL
|3 days||2 months||2 months|
Reporting units: ng/mL; ng/mg Creatinine (normalized)
Biological or Clinical Significance:
Beta-2-microglobulin (ß2-M) M is a small globular peptide with a molecular weight of 11800 D. It consists of 100 amino acids with a disulfide-linked loop between amino acid 25 and 81 and its tertiary structure is homologous to the CH3 -IgG immunoglobulin domain.
ß 2-M is normally cleared exclusively by the kidneys. It passes freely through the glomerular membrane, and then is reabsorbed to an amount of up to 99.9% by the proximal tubules. It is present in small amounts in serum, csf, and urine of normal people, and to a much greater degree in the urine and plasma of patients with tubular proteinemia, renal failure, or kidney transplants. In addition, it has been reported that other increased serum levels are found in rheumatoid arthritis and autoimmune diseases.
Principle of Test Method:
The Beta-2-microglobulin assay is an automated immunoturbidimetric method.
Beta-2-microglobulin is reported as a normalized ratio to urinary creatinine in order to account for variations in urine flow rate. Therefore ß 2-M and urine creatinine are preferably tested from the same aliquot.