Accuracy of Blood Versus Urine Assays in Diagnosis of Multiple Myeloma
Posted: Thursday, August 23, 2018
The results of a recent study published in the Journal of Clinical Medicine Research found that when clinicians use serum-free light chain assays to detect monoclonal gammopathies in patients with multiple myeloma, about 25% of individuals may not be diagnosed appropriately. These findings indicate the importance of utilizing urine protein electrophoresis and urine protein immunofixation electrophoresis to accurately identify the disease. Urine protein electrophoresis as a tool for identifying monoclonal gammopathies is underutilized compared with the standard serum free light chain assay, the researchers noted.
“When you test the serum, we suggest you also test the urine whenever you suspect that somebody has a tumor of the plasma cells,” stated Gurmukh Singh, MD, PhD, MBA, of the Medical College of Georgia (MCG) at Augusta University, in an institutional press release.“If you have a lambda chain–associated lesion and you don’t do a urine study, just rely on the serum free light chain assay, about 1 out of 4 times, the assay will tell you that you don’t have anything when you actually do,” revealed study coauthor Won Sok Lee, MD, also of MCG.
Drs. Singh and Lee conducted a retrospective analysis of 175 patients who underwent serum protein electrophoresis, urine protein electrophoresis, and serum free light chain assay. Normal kappa light chain to lambda light chain ratios were observed in 25% of patients, yet free homogenous lambda light chains were detectable through urine tests. False-negative results were found in 30% of patients, 5% of which were due to the underproduction of lambda free light chains.
