Proposed Method Using the Urinary Albumin-To-Total Protein Ratio for Detection of Urinary Bence Jones Protein

Detecting urinary Bence Jones protein (BJP) is effective for early diagnosis of malignant diseases, such as multiple myeloma. Currently, BJP is detected by heat coagulation test (Putnam's method), immunoelec-trophoretic (IEP) analysis, and immunofixation electrophoresis (IFE). However, because of their low sensitivity, high cost, and labor intensiveness, alternative biomarkers are being sought. The study aimed to evaluate the use-fulness of the urinary albumin/total protein (U-ALB/U-TP) ratio for early detection of urinary BJP.

U-ALB and U-TP were measured in 85 BJP urine samples confirmed by IEP or IFE and 507 samples from the general patient group, for a total of 592 samples. A total of 592 general patient samples were used to calculate the U-ALB/U-TP ratio for receiver operator characteristic (ROC) curve analysis.

The correlation between U-TP and U-ALB was strong in the general group but weak in the BJP group. For a BJP detection cutoff value obtained by ROC curve analysis of 0.362 (area under the curve: 0.941), the sensitivity was 92% and the specificity was 88% for a U-TP ≥ 30 mg/dL. A decreased ratio of U-ALB/U-TP indicates turbid urine (high white blood cell count), bacteriuria, crystalluria, or high urinary free L chain as well as urinary BJP.

We demonstrated that BJP could be detected by measuring the U-ALB/U-TP ratio, which may enable early detection of BJP in patients with malignant diseases at the presymptomatic stage.