Low molecular weight urinary proteins and renal lithiasis.

Twenty-four hour urine specimens were obtained from 20 active calcium oxalate stone formers, 20 inactive calcium oxalate stone formers, 8 struvite stone formers, and 9 non-stone forming controls. Proteins with molecular weights less than 50,000 daltons were concentrated by ultrafiltration and separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Fourteen of the 17 active calcium oxalate stone formers had low molecular weight urinary proteins (less than 35,000 daltons) present in their urine whereas none of the inactive stone formers or struvite stone formers had similar patterns. Only one of the nine control patients had similar proteins present.