Biomarkers are an important clinical assessment tool in medicine as they are measurable indicators of biological processes in the body. In the field of nephrology, biomarkers can be used to estimate the severity and nature of kidney function or injury. An article by Yale nephrologists published August 10 in the Clinical Journal of the American Society of Nephrology reports on a new biomarker for kidney fibrosis. Fibrosis, the formation of internal scar tissue, is often seen in patients with chronic kidney disease.
The biomarker, uromodulin, is a protein made only in the kidneys. Also called Tamm-Horsfall protein, it is produced exclusively in the thick ascending limb of the loop of Henle, which is central to renal physiology. As one of the most abundant proteins in the urine, uromodulin is an attractive biomarker of kidney health, said Dennis Moledina, MD, PhD, assistant professor (nephrology) at Yale School of Medicine (YSM) and senior author of the study.
Many observational studies have shown that lower levels of urine uromodulin are strongly associated with greater decline in kidney function, but the explanation for this association has not been clear, said co-first author Frida Calderón-Gutiérrez, a postgraduate associate at YSM. “We hypothesized that lower urine uromodulin reflected greater degree of kidney tissue replaced by fibrosis, and predicted that lower urine uromodulin levels would strongly associate with interstitial fibrosis,” Calderón-Gutiérrez said.
Hannah Melchinger, also co-first author and a postgraduate associate at YSM, said the study found that interstitial fibrosis/tubular atrophy was independently associated with urine uromodulin levels. The authors added that lower urine uromodulin levels indicate that a greater portion of healthy kidney tubulointerstitial tissue is replaced by fibrosis, and that urine uromodulin may provide additional information on kidney tubular health for which there are currently no biomarkers.
"Urine uromodulin as a biomarker of kidney tubulointerstitial fibrosis," may be read here.