What is the normal level of beta-2 microglobulin (β2M)?

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Last updated: May 15, 2025View editorial policy

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From the Guidelines

Beta-2 microglobulin (B2M) normal levels in serum typically range from 0.7 to 3.4 mg/L (or 0.7 to 3.4 μg/mL) for adults. This small protein is found on the surface of nearly all nucleated cells and is particularly abundant on white blood cells. B2M is constantly released into the bloodstream during normal cell turnover and is primarily filtered by the kidneys. Elevated levels often indicate increased cell turnover (as seen in lymphoproliferative disorders, multiple myeloma, and some inflammatory conditions) or decreased renal clearance (as in kidney disease) 1.

Key Points to Consider

  • B2M levels are particularly useful in monitoring disease activity in multiple myeloma and as a prognostic marker in certain lymphomas 1.
  • For accurate interpretation, B2M results should always be considered alongside kidney function tests since impaired renal function can cause elevated levels even without increased cell turnover.
  • Regular monitoring of B2M can help track disease progression or response to treatment in relevant conditions.
  • In the context of kidney disease, B2M serum levels can be 15 to 30 times greater than normal, leading to potential complications such as beta-2 microglobulin amyloidosis (A2M) 1.
  • The clinical manifestations of A2M can include carpal tunnel syndrome, spondyloarthropathies, hemarthrosis, and joint pain and immobility, making early detection and monitoring crucial 1.

From the Research

Beta 2 Microglobulin Normal Levels

  • The normal level of beta 2 microglobulin (beta 2M) can vary depending on the laboratory and measurement technique used 2, 3.
  • In general, a normal beta 2M level is considered to be less than 2.5 mg/L, although this can vary slightly depending on the specific assay used 4, 5.
  • Elevated beta 2M levels have been associated with a range of conditions, including multiple myeloma, lymphoma, and leukemia 2, 3, 6.

Prognostic Significance of Beta 2M

  • Beta 2M levels have been shown to be a significant prognostic factor in a range of hematological malignancies, including multiple myeloma, chronic myelogenous leukemia, and malignant lymphoma 3, 4, 5, 6.
  • Elevated beta 2M levels have been associated with a poorer prognosis and a higher risk of disease progression in these conditions 2, 3, 4, 5.
  • Beta 2M levels can be used in combination with other prognostic factors to stratify patients into different risk groups and guide treatment decisions 5, 6.

Measurement and Interpretation of Beta 2M

  • Beta 2M levels can be measured using a range of techniques, including radioimmunoassay and enzyme-linked immunosorbent assay (ELISA) 2, 3.
  • The interpretation of beta 2M levels requires careful consideration of the clinical context and other prognostic factors, as well as the specific assay used to measure beta 2M 4, 5, 6.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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