The optimum urine collections for the detection and monitoring of Bence Jones proteinuria

Twenty patients with malignant disease and Bence Jones (BJ) proteins were studied to determine the optimum urine collections for the detection and monitoring of light chain proteinuria. A 24-hour urine protein collection was followed by individual collections of each sequentially voided specimen over the same time interval. Samples were analyzed quantitatively for protein, and protein electrophoresis was performed on each specimen. Only one patient had BJ protein nondetectable by protein electrophoresis in the early morning specimen. Six patients had one or more random specimens (excluding the early morning specimens) absent for BJ protein on protein electrophoresis. Three patients had nondetectable protein on electrophoresis of the 24-hour specimen despite having some random specimens positive. All random specimens with protein values exceeding 0.20 g/L had BJ protein visibly detectable on electrophoresis. Thirteen specimens with protein less than 0.05 g/L still had BJ protein detected by electrophoresis. There was a linear relationship between the early morning protein concentration and the total 24-hour urinary protein production. The authors conclude that early morning specimens or 24-hour urine collections are preferable for the detection and monitoring of light chain proteinuria. These collection methods are not mutually exclusive because there are individual patients who will be negative in one collection but positive in the other.