Serum uromodulin helps identify residual kidney function in hemodialysis patients

Monitoring residual kidney function can inform incremental hemodialysis prescriptions, but timed interdialytic urine collections are cumbersome. In a prospective observational study at two centers in Geneva, Switzerland, researchers measured predialysis serum uromodulin and β2-microglobulin in 151 patients. They compared these biomarkers with urine-derived residual urea clearance (KRU), targeting identification of KRU ≥2 mL/min/35L.

Overall, 59 patients (39%) met this threshold. Uromodulin had an area under the receiver operating characteristic curve (AUC) of 0.891 (95% CI 0.839–0.944), compared with 0.877 for β2-microglobulin (P=0.66). Combining the markers increased the AUC to 0.923 (95% CI 0.883–0.964), outperforming uromodulin alone (P=0.03) and β2-microglobulin alone (P=0.01).

A grey-zone strategy used separate rule-out and rule-in cutoffs targeting at least 90% sensitivity and specificity, respectively. Uromodulin alone classified 76% of patients without urine collection, with a negative predictive value of 97% and positive predictive value of 84%; the combined model classified 85%.

These findings suggest complementary biomarkers could reduce urine-collection requirements when assessing eligibility for incremental hemodialysis. However, this two-center observational study assessed diagnostic discrimination rather than the safety or clinical outcomes of biomarker-guided dialysis prescribing. External validation is not reported in the supplied text.