*Article* **Elevated Levels of Renalase, the** β**-NAD(P)H Isomerase, Can Be Used as Risk Factors of Major Adverse Cardiovascular Events and All-Cause Death in Patients with Chronic Kidney Disease**

**Wojciech Knop 1, Natalia Maria Serwin 2,\*, Elzbieta Cecerska-Hery´ ˙ c 2, Bartłomiej Grygorcewicz 2, Barbara Doł ˛egowska 2, Aleksandra Gomółka 1, Magda Wi´sniewska <sup>1</sup> and Kazimierz Ciechanowski <sup>1</sup>**


**Citation:** Knop, W.; Serwin, N.M.; Cecerska-Hery´c, E.; Grygorcewicz, B.; Doł ˛egowska, B.; Gomółka, A.; Wi´sniewska, M.; Ciechanowski, K. Elevated Levels of Renalase, the β-NAD(P)H Isomerase, Can Be Used as Risk Factors of Major Adverse Cardiovascular Events and All-Cause Death in Patients with Chronic Kidney Disease. *Biomolecules* **2021**, *11*, 1514. https://doi.org/10.3390/biom 11101514

Academic Editor: Liang-Jun Yan

Received: 28 July 2021 Accepted: 9 October 2021 Published: 14 October 2021

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**Abstract:** Background: Renalase is an enzyme and a cytokine involved in cell survival. Since its discovery, associations between it and both cardiovascular and kidney disease have been noted. Recognizing this, we conducted a study in which we followed patients with chronic kidney disease. Material and methods: The study involved 90 CKD patients with varying stages of the disease and 30 healthy controls. Renalase was measured with an ELISA kit, and patients were followed-up after a median of 18 months. During the follow-up, we asked about the occurrence of MACE, all-cause mortality and the need for dialysis initiation. Results: In CKD subgroups, RNSL correlated with all-cause death only in the HD group (Rs = 0.49, *p <* 0.01). In the whole CKD population, we found a positive correlation of RNSL concentration and both MACE occurrence (Rs = 0.38, *p <* 0.001) and all-cause death (Rs = 0.34, *p <* 0.005). There was a significant increase in MACE occurrence probability in patients with elevated renalase levels (>25 μg/mL). Conclusions: Elevated renalase levels can be used as a risk factor of MACE in patients with CKD, but its long-term utility needs further research. High renalase levels are a risk factor of death among CKD patients. In HD patients, all deaths were observed among patients with >30 μg/mL; this level could be used as a "red flag" marker in future studies.

**Keywords:** renalase; chronic kidney disease; major adverse cardiovascular outcomes
