What does an α‑2‑microglobulin level of 320 µg/L signify and what evaluation should be pursued?

α-2-Microglobulin Elevation at 320 µg/L: Clinical Significance and Management

A β2-microglobulin level of 320 µg/L (0.32 mg/L) is well below the normal upper limit of 2 mg/L and does not indicate renal disease, dialysis-related amyloidosis, or any pathological condition requiring intervention. 1

Understanding the Result

• Normal β2-microglobulin serum concentration is less than 2 mg/L (2000 µg/L) in healthy individuals, making your value of 320 µg/L completely within normal range. 1

• β2-microglobulin is an 11,800 Da nonglycosylated polypeptide that is normally filtered by the glomerulus and metabolized by the kidney. 1

• The protein functions as part of the HLA complex on cell surfaces and is synthesized and shed by many cells, particularly lymphocytes. 2

When β2-Microglobulin Becomes Clinically Significant

Renal Disease Context

• Dialysis patients typically have β2-microglobulin levels 15-30 times greater than normal (30-60 mg/L or 30,000-60,000 µg/L), which is approximately 100-200 times higher than your reported value. 1, 3

• Elevated serum β2-microglobulin only occurs with impaired renal function when creatinine clearance falls below 70-100 mL/min. 4, 5

• Serum β2-microglobulin has a coefficient of -0.87 with creatinine-derived glomerular filtration rate, making it an excellent marker of renal function when truly elevated. 5

Dialysis-Related Amyloidosis

• β2-microglobulin amyloidosis manifests clinically 2-10 years after dialysis initiation with carpal tunnel syndrome, spondyloarthropathies, hemarthrosis, and joint pain with immobility. 1, 6

• Screening for β2-microglobulin amyloidosis, including measurement of serum levels, is not recommended because no effective therapy exists except kidney transplantation. 1

Clinical Pitfalls to Avoid

• Do not confuse α-1-microglobulin (normal range 20-42 mg/L) with β2-microglobulin (normal range <2 mg/L) - these are different proteins with different clinical significance. 4

• β2-microglobulin can be transiently elevated during febrile illness without renal disease, but remains well below 10 mg/L in these situations. 5

• In patients with actual β2-microglobulin amyloidosis, clinical symptoms may not correlate with serum levels, making the measurement of limited utility even when truly elevated. 3

No Further Evaluation Required

• Your value of 320 µg/L requires no additional workup, imaging, or specialist referral. 1

• If there was concern about renal function, assess creatinine clearance directly rather than relying on β2-microglobulin at this normal level. 4, 5