The Effect of Body Mass Index on the Degree of Renal Interstitial Fibrosis and Tubular Atrophy - A Retrospective Case-Control Study

Abstract

Introduction The degree of interstitial fibrosis and tubular atrophy (IFTA) seen on kidney biopsy has long been used to judge the chronicity of kidney disease to predict renal disease outcomes and prognosis. It is an essential component incorporated in many renal disease prognostic classification systems on the native and renal allograft. The impact of increased body mass index on the body metabolism, and the human vascular system, including the functional unit of the kidney, the nephron, is well-addressed in the literature. In this study, we focus on evaluating the degree of IFTA concerning the patient's body mass index (BMI). Method All the specimens of nephrectomies performed in King Abdulaziz University Hospital for adults from January 2010 to February 2021 were evaluated for this study. A total of 125 cases were selected for the study. The glass slides were pulled and assessed for the degree of IFTA. The demographic data, and the patient's BMI, were collected from the hospital records. Results Subjects with high BMI showed a 1.62 (OR: 1.62, 95% CI: 0.62, 4.22) and 1.52 (AOR: 1.52, 95% CI: 0.56, 4.13) increased risk of high IFTA score compared with those with normal BMI. This study has proved that only at a BMI of 25 or more will there be a measurable, independent effect on the degree of IFTA. Conclusion Although a small number of hospital-based populations limits this study, it could prove the increased severity of IFTA in patients with high BMI. Its result may act as a spark that will drive extensive population-based studies that more precisely delineate the relationship between BMI and the degree of IFTA on different levels.

Keywords: bmi and kidney; interstitial fibrosis and tubular atrophy; obesity and renal interstitium; obesity and renal tubules; renal health in obesity; renal scarring.

Figure 1. Kidney tissue with an area of interstitial fibrosis and tubular atrophy

A light microscopic picture of one of our studied cases, showing kidney tissue with an advanced degree of IFTA and glomerular sclerosis. The yellow arrows indicate the area of interstitial fibrosis, while the blue arrows indicate the atrophic tubules with narrow lumen, hyaline cast, and thick basement membrane.