C3 and chronic kidney disease: Patients with higher TA-SUA levels were more likely to be male and to have hypertension, and these patients also had higher levels of baseline SUA, BUN and TG, more proteinuria, worse renal function and CKD stage, more complement activation including higher levels of serum C3 and serum C4, and more serious renal pathological injuries including a higher grade of tubular atrophy/interstitial fibrosis, compared with patients with TA-SUA levels in the lowest quartile.