Beta-2 Microglobulin (B2M) Test Cost & Procedure

Beta-2 microglobulins are proteins that are present on the surface of cells. It belongs to MHC (Major histocompatibility complex) class 1 molecules. It is encoded by gene B2M. It is a metabolite that is used in assessing renal function . It can also be a non-specific marker for conditions such as infectious, neoplastic and inflammatory.

Major histocompatibility complex

It is a complex containing a group of genes that encodes for proteins. These proteins are necessary for adaptive immune response.

MHC complex is composed of 3 components

• MHC Class 1
• MHC Class 2
• MHC Class 3

MHC Class 1 and 2 molecules encode for proteins that are directly involved in presentation of antigen.

Significance of beta-2 microglobulins:-

The increased values of beta -2 microglobulin in blood and urine is suggestive of tumour and renal disorder.

beta-2 microglobulin values in urine tell about disorders related to renal filtration. Beta-2 microglobulin levels are measured in both serum and urine to distinguish problem cellular activation from renal disorder.

Normal range of b-2 microglobulin:

• Blood: 0.70-1.80 mcg/mL
• Urine: ≤300 mcg/L
• Cerebrospinal fluid (CSF): 0-2.4 mg/L

In normal conditions, beta-2 microglobulins are freely filtered over glomeruli as they are low molecular proteins. 99.99 % of this protein is reabsorbed in proximal tubules of the kidney and metabolised. In renal disease there is more excretion of beta-2 microglobulin protein leading to increased levels in urine. The reduced rate of glomerular filtration leads to increased levels of serum-beta 2M.

Serum-beta 2M is raised in numerous malignant diseases therefore acts as a tumour marker. It also reflects the size of the tumour mass. In the tumour marker test Beta-2 microglobulin levels are measured in body fluids. Mostly blood samples are used to measure the levels, urine can also be used.

Normally, there is a small amount of B2M in the blood and urine. High levels of B2M in body fluids are due to blood and bone marrow cancers:

• Multiple myeloma
• Chronic lymphocytic leukeamia(CLL)
• Certain types of lymphoma

In the Tumour marker test blood sample or 24 hours urine sample is used. In rare comditions cerebrospinal fluid may be used.

>> Blood sample- collected from a vein.

>> Urine sample- 24 hours urine is collected in a special container.

CSF sample- collected by lumbar puncture. A provider numbs your skin with medicine and uses a thin, hollow needle to remove some fluid from between the bones in your lower spine. You usually go home the same day.