CST3 and Renal artery stenosis: [21] Another cross-sectional study in general population in the National Health and Nutrition Examination Survey (NHNES) 1999 to 2002 also demonstrated that GFR estimated using cystatin C was strongly associated with PAD. [22] The possible mechanisms underlying the close relationship between renal disease and PAD were the co-progression of renal artery stenosis and overall atherosclerosis including lower extremity vascular disease, [23] and excessive accumulation of metabolic wastes due to reduced GFR. [24].