From the Guidelines
Urine beta-2 microglobulin should be checked as part of the initial diagnostic workup in patients with suspected multiple myeloma, particularly to assess tumor cell burden and kidney function, as indicated by the NCCN Guidelines for MM 1. When evaluating patients for multiple myeloma, it is essential to assess various markers, including beta-2 microglobulin, to determine the extent of disease and potential kidney involvement.
- The test is valuable in assessing tumor cell burden, as increased levels of beta-2 microglobulin reflect a higher tumor load 1.
- Additionally, beta-2 microglobulin levels can indicate decreased kidney function, which is a common complication in multiple myeloma patients 1.
- The NCCN Guidelines for MM recommend including beta-2 microglobulin as part of the initial diagnostic workup, along with other blood studies and biological assessments, to differentiate between symptomatic and asymptomatic multiple myeloma 1.
- It is crucial to interpret beta-2 microglobulin levels in conjunction with other markers of kidney function, such as serum creatinine and blood urea nitrogen, to obtain a comprehensive assessment of the patient's condition 1.
From the Research
Urine Beta-2 Microglobulin Check
- Urine beta-2 microglobulin is checked to detect renal tubular damage, particularly in patients receiving aminoglycosides for treatment of infection 2, 3, 4, 5.
- The test is non-specific, but it can herald aminoglycoside-induced damage before standard tests of kidney function change 2.
- Increased beta-2 microglobulin excretion can be seen in patients with pyelonephritis, but its measurement is not a reliable indicator of renal involvement in urinary tract infections 3.
- Serial monitoring of proximal tubular function with urinary beta-2 microglobulin excretion has potential value in the assessment of insults to this site, but cannot be expected to explain all changes in serum creatinine 4.
Timing of Urine Beta-2 Microglobulin Check
- Urinary beta-2 microglobulin excretion rises 5 days or more before serum creatinine rises in patients who develop aminoglycoside nephrotoxicity 2.
- The laboratory diagnosis of nephrotoxicity, defined as a two-fold increase in beta 2-microglobulin, can be made 4.1-5.5 days prior to significant elevation in serum creatinine 5.
- An elevation in beta 2-microglobulin excretion above the baseline value occurs in 71% of patients treated with aminoglycosides, whereas the serum creatinine concentration rises in only 33% of patients 4.
Clinical Applications
- Measuring urinary concentrations of beta-2 microglobulin during aminoglycoside treatment can be used to compare the nephrotoxic potential of different aminoglycosides and possibly of other antimicrobial agents 3.
- Beta-2 microglobulin level monitoring can be used in conjunction with other variables to guide renal replacement therapy in patients with chronic kidney disease 6.