What does it mean when β2-microglobulin is high?

Elevated serum β2-microglobulin levels may result from one of three conditions: reduced glomerular filtration of β2-microglobulin, overproduction of β2-microglobulin, or impaired excretion of β2-microglobulin.

1. Reduced glomerular filtration of β2-microglobulin

When certain diseases cause a decline in glomerular filtration rate, the amount of β2-microglobulin filtered through the glomeruli decreases, leading to elevated concentrations in the blood. This indicates impaired glomerular function and is commonly seen in conditions such as diabetic nephropathy and chronic glomerulonephritis.

2. Overproduction of serum β2-microglobulin

This is most commonly associated with malignant disorders, particularly lymphoma and multiple myeloma. Patients with multiple myeloma often exhibit markedly elevated serum β2-microglobulin levels, which serve as an important diagnostic criterion. The greater the increase in β2-microglobulin, the more severe the disease and the poorer the prognosis.

3. Impaired excretion of β2-microglobulin

This condition is typically observed in kidney damage. It mainly results from decreased reabsorption of β2-microglobulin by the proximal renal tubules, leading to reduced excretion. β2-microglobulin is considered a relatively sensitive marker for assessing renal tubular injury.

In addition to the above relatively common causes, other possible conditions include systemic lupus erythematosus during active phases.