Kidney Pathological Changes in Metabolic Syndrome: A Cross-sectional Study

Background: The worldwide prevalence of metabolic syndrome is increasing and has been associated with chronic kidney disease. Kidney pathological findings in patients with metabolic syndrome have not been well described, as was explored in this study. Study Design: Cross-sectional study. Setting & Participants: We retrospectively screened clinical information for 146 patients who underwent elective nephrectomy for renal cell carcinoma between January 2005 and March 2007 at Brigham and Women's Hospital, Boston, MA. Twelve patients with metabolic syndrome were identified. Twelve age- and sex-matched patients who did not have any of the criteria for metabolic syndrome were used as controls. Predictor: Presence of metabolic syndrome defined by using Adult Treatment Panel III criteria. Outcomes: Histological characteristics in each group, decrease in kidney function at 1-year follow-up. Measurements: Two pathologists blinded to the clinical diagnosis independently evaluated nephrectomy specimens using Banff criteria to objectively assess histological characteristics. Results: Baseline characteristics were similar between the 2 groups. On histopathologic examination, patients with metabolic syndrome compared with controls had a greater prevalence of tubular atrophy (P = 0.006), interstitial fibrosis (P = 0.001), and arterial sclerosis (P = 0.001), suggesting microvascular disease. Patients with metabolic syndrome had greater global (P = 0.04) and segmental glomerulosclerosis (P = 0.05). Glomerular volume and cross-sectional surface area were not different. The combined end point of tubular atrophy greater than 5%, interstitial fibrosis greater than 5%, and presence of arterial sclerosis was more prevalent in patients with metabolic syndrome (P = 0.003; odds ratio, 33; confidence interval, 2.9 to 374.3) than controls. After 1 year, estimated glomerular filtration rate was significantly lower in patients with metabolic syndrome compared with controls (P = 0.03). Limitations: Small sample size, retrospective design. Conclusions: We report a high prevalence of microvascular disease in patients with metabolic syndrome. There was a steeper decrease in kidney function over time in patients with metabolic syndrome, suggesting limited renal reserve. Aggressive screening and management may be warranted in patients with metabolic syndrome to protect kidney function.