16] Facts About: Major Glycoprotein in Urine – Uromodulin/Tamm-Horsfall Protein (THP)

Water Loading and Uromodulin Secretion in Healthy... : Clinical Journal of the American Society of Nephrology

completely understood. Methods: We investigated changes in uromodulin levels and key factors governing its production and release in the urine and serum. We performed an experiment to determine if water loading, a common intervention to prevent stone formation, will alter the rate of uromodulin production. During a two-day period, 17 stone forming participants and 14 control participants were subjected to water loading (day 1) and normal fluid intake (day 2). Uromodulin levels were measured on timed hourly collections in the urine and plasma during the period of the study. Results: Water loading increased urinary uromodulin secretion (33 ± 4 vs. 10 ± 4 μg/min at baseline, p <0.0001) in stone former and control participants. Despite high urine volumes, most participants maintained relatively stable urinary uromodulin concentrations. Native Western blots for polymerizing and non-polymerizing uromodulin suggest that polymerizing uromodulin was the predominant form at higher urinary flow volumes. Urine flow rates and sodium excretion were significant correlates of urinary uromodulin production. Water loading did not affect serum uromodulin levels, which were also not associated with urinary uromodulin. Conclusions: Water loading increases the secretion of polymerizing urinary uromodulin. This increased secretion reduces the variability of urinary uromodulin concentrations despite high urine volumes. Serum uromodulin levels were not impacted by this treatment. Copyright © 2023 by the American Society of Nephrology...