The role of urinary renalase on early-stage renal damage in Chinese adults with primary hypertension.

Unlabelled: It would be of great clinical value to find an indicator that can accurately evaluate the early-stage renal injury in primary hypertension. Previous findings have shown renalase not only plays an important role in hypertension but also closely correlates with kidney function. The purpose of this study is to investigate whether urinary renalase could be used as a predictive index of early-stage renal damage in patients with primary hypertension. Urinary albumin to creatinine ratio (UACR) was used to divide subjects with primary hypertension into two groups: a no renal damage (NRD) group (UACR <30 mg/g) and an early-stage renal damage (RD) group (UACR >30 mg/g). Subjects with normal examination results were randomly included in a healthy control (HC) group. Urinary renalase was determined through an enzyme-linked immunosorbent assay (ELISA). Urinary renalase continued to reduce among the HC (n = 81), NRD (n = 84) and RD group (n = 80), while systolic blood pressure (SBP) increased. Urinary renalase was negatively correlated with SBP in all the groups. Among the subjects with stage 1 primary hypertension, urinary renalase in the RD group was lower than the NRD group, while the UACR was higher, and urinary renalase was negatively correlated with the UACR. A multiple linear stepwise regression analysis showed that there was a linear regression relationship between the increase of the UACR and urinary renalase, heart rate (HR), SBP and serum creatinine. In addition, the standardized partial regression coefficient of urinary renalase was the highest. The performance of urinary renalase as a marker for the diagnosis of early-stage renal damage in patients with primary hypertension was 0.968 with a cut off value of 2.01 µg/ml. Taken together, urinary renalase was further decreased in patients with early-stage renal damage and primary hypertension, and consequently, it could be used as a predictive index.

Impact Statement: In patients with early-stage kidney damage of primary hypertension, there are no obvious structural or functional changes, which leads to a high level of diagnostic omissions. Therefore, it would be of great clinical value to find an indicator that can accurately evaluate the early-stage renal injury in primary hypertension. Urinary albumin to creatinine ratio (UACR) is a classic indicator used in early-stage renal damage, but it is affected by many factors. Renalase, a protein discovered by Xu in 2005, not only plays an important role in hypertension but also closely correlates with kidney function. In our study, we found that urinary renalase was further decreased in patients with early-stage renal damage in primary hypertension, and it could be used as a predictive index. This finding could help to diagnose the early-stage renal damage in primary hypertension much earlier and improve the prognosis of these patients.