Use

Quantitative measurement of urine free kappa and lambda light chains, along with immunofixation, is useful in monitoring disease progression or response to therapy when urine electrophoresis cannot reliably quantify Bence Jones protein. However, results may be misleading in specimens with high levels of urinary polyclonal free light chains and absent Bence Jones protein; correlation with urine immunofixation is required. Total urinary protein is measured turbidimetrically, which may differ from chemical determination and underestimate light chains. Antigen excess cannot be excluded.