REN and chronic kidney disease: According to studies, increased cardiovascular risk in patients with CKD is multifactorial and involves both traditional (hypertension, diabetes, dyslipidemia) and kidney-specific risk factors, such as enhanced activity of the renin–angiotensin system (RAS) and sympathetic overactivity, endothelial dysfunction (related to the accumulation of asymmetric dimethylarginine, chronic inflammatory state, and oxidative stress), hyperphosphatemia as well as CKD-associated metabolic bone disorder (CKD-MBD) [8,10,11].