CRP and chronic kidney disease: Although the previous longitudinal studies have examined the association between CRP levels and CKD in different populations, evidence on the causality of this association remains controversial.5–7 However, some researchers demonstrated the effect of CRP-oriented biological functions on kidney function.8,9 One researcher also has published a meta-analysis suggesting that vitamin D supplementations could lower circulating CRP levels.10 Taken together, these studies suggest that interventions on CRP may help to improve renal function.