REN and chronic kidney disease: Even in early CKD (stages 1 and 2; eGFR >60 mL/min per 1.73 m2), subclinical signs of early inflammation can be detected, including small increases in inflammatory markers such as CRP (C-reactive protein) and IL-6.64 The renin-angiotensin-aldosterone system starts to become more active, which can lead to inflammation and fibrosis over time.65