Improved measurement of urinary total protein (including light-chain proteins) with a Coomassie brilliant blue G-250-sodium dodecyl sulfate reagent.

The Coomassie Brilliant Blue G-250 method for urinary proteins underestimates urinary immunoglobulin light chains when albumin or pooled serum is used as the protein standard. The specific color yields of these and other proteins can be brought closer together by adding sodium dodecyl sulfate to the reagent; however, there is some loss of sensitivity. We found such a reagent to be satisfactory for assaying urinary proteins on studying 43 patients with light-chain proteinuria, 19 of whom had multiple myeloma and six possible multiple myeloma.