Serum-to-urine renalase ratio and renalase fractional excretion in healthy adults and chronic kidney disease patients

Abstract

Background: Renalase is a flavoprotein that plays a protective role in chronic kidney disease (CKD) and cardiovascular diseases. The secretion and way of action of this protein are still discussed. The aim of our study was to estimate the balance between serum and urine renalase in healthy individuals and CKD patients, using two parameters: fractional excretion (FE) and serum-to-urine renalase ratio (StURR). Methods: Our study involved 28 healthy volunteers and 62 patients with CKD in stages I to IV. The concentration of renalase in serum and urine was measured using an enzyme-linked immunosorbent assay (ELISA) kit (EIAab, Wuhan, China). We analyzed associations between renalase levels in urine and serum, and other parameters: sex, age, GFR, presence of hypertension, diabetes, and proteinuria, and determined the serum-to-urine renalase ratio and fractional excretion of renalase. Results: Renalase and serum-to-urine ratio were significantly higher in CKD patients in comparison with the control group. Fractional excretion was lower in CKD patients but this difference did not reach the statistical significance (p = 0.092). Multivariate analysis performed in the CKD group showed, that from mentioned parameters, serum renalase was the only significant independent factor strongly positively associated with urinary renalase concentration. Conclusions: The serum-to-urine ratio is significantly and about 6.5-fold higher in CKD patients, and the fractional excretion of renalase is 3-fold, but not significantly lower in CKD patients. Renalase levels in both serum and urine are not related to the glomerular filtration rate and not associated with blood pressure.

Renal and Inflammation Markers—Renalase, Cystatin C, and NGAL Levels in Asymptomatic and Symptomatic SARS-CoV-2 Infection in a One-Month Follow-Up Study

“…As shown in CKD patients, serum renalase remains at a significantly higher level than in healthy persons, indicating that this protein is not only overproduced in CKD but is also stopped from escaping the blood by a yet unknown mechanism that occurs during kidney injury or dysfunction. This assumption is supported by the fact that both urinary renalase itself and after normalization to creatinine do not differ between healthy adults and renal patients [ 9 , 38 ]. In the present study, renalase levels were significantly higher in the COVID-19 patients from day 7 of observation until its end on day 28.…”

The influence of cord blood renalase and advanced oxidation protein products (AOPPs) on perinatal and anthropometric parameters of newborns of mothers with gestational hypertension

“…6,7 Genetic investigations have revealed the occurrence of single nucleotide polymorphisms (SNPs) in the renalase gene and the association of some of them with selected cardiovascular diseases, kidney diseases, type 1 diabetes, ischemic stroke, female infertility schizophrenia, as well as gestational HT and preeclampsia. [8][9][10][11][12] Renalase is secreted into the blood mainly by the kidneys, but its expression has also been shown in many other organs and tissues such as heart, skeletal muscles, endothelium, small intestine, adipose tissue, brain, liver, as well as in the reproductive/steroidogenic system, which is an interesting finding in the context of this study. 13,14 Oxidative stress takes part in the development of numerous pathologic conditions and by affecting the prenatal life it may have a deleterious effect by causing perinatal disorders and subsequent neonatal diseases.…”