Predictive Value of Free Light Chain Ratio and Urinary M-Protein for Renal Involvement and Disease Progression in Multiple Myeloma

Open Access

Abstract

Background: Renal impairment is a frequent and serious complication of multiple myeloma (MM), often leading to poor prognosis. Serum free light chain (FLC) ratio and urinary M-protein are emerging biomarkers with potential predictive value for renal involvement and disease progression. Aim of the study: To evaluate the predictive value of serum FLC ratio and urinary M-protein levels for renal involvement and disease progression in patients with multiple myeloma. Methods & Materials: This prospective observational study was conducted at Bangabandhu Sheikh Mujib Medical University (BSMMU), Dhaka, from April 2023 to September 2024, including 54 MM patients. Clinical, biochemical, and renal parameters were analyzed. Statistical comparisons and multivariate logistic regression were performed to identify independent predictors of renal impairment. Result: Renal impairment was observed in 66.7% of patients. Mean serum FLC ratio and urinary M-protein were significantly higher in patients with renal dysfunction (p=0.002 and p=0.011, respectively). Both markers correlated positively with serum creatinine and β₂-microglobulin and inversely with eGFR. Multivariate analysis identified elevated FLC ratio (>10), urinary M-protein (>150 mg/24h), and β₂-microglobulin (>5 mg/L) as independent predictors of renal involvement. Conclusion: Elevated FLC ratio and urinary M-protein are strong, independent predictors of renal involvement and disease progression in multiple myeloma. Early assessment of these biomarkers can facilitate prompt intervention, preserve renal function, and improve prognosis.