Analyses of urine samples collected from children and adults provide the first comprehensive catalog of urinary calcium oxalate monohydrate (COM) binding proteins and reveals significant differences in the level and make-up of these proteins between the two populations, urologists from Washington University School of Medicine, St. Louis, reported at the AUA annual meeting in San Diego.
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The study, which included subjects with no history of urinary stone disease (USD), is part of a larger ongoing project aiming to characterize the urinary proteome in children and adults for insights on USD pathogenesis as well as age-related clinical differences, and eventually to guide development of better prognostic approaches and therapeutic strategies.
“In previous work, we demonstrated there are populations of proteins within human urine that have very high affinity for COM. In addition, we showed that some of these proteins inhibit crystal adhesion and crystal growth and aggregation in solution,” said first author Joel Koenig, MD.
“So far, in this phase of our research, we have found there are age-related differences in the urinary proteome and specifically with regard to COM-binding proteins. Moving ahead, we are conducting additional analyses to better characterize the differences,” added Dr. Koenig, who worked on the study with Paul Austin, MD, and colleagues.
Findings from basic chemistry studies done to measure the concentration of various proteins in the urine samples along with affinity chromatography performed using control and COM crystal-loaded columns showed that in both the pediatric and adult subjects, proteins with a high selective affinity for COM comprised a minor proportion of the total protein content of the urine. Consistent with some previous research, the proportion of proteins with a high selective affinity for COM accounted for only about 10% to 20% of total protein in the urine, Dr. Koenig reported.