Determinants of renal shape in chronic kidney disease patients

Abstract

Background: The determinants of renal shape are not well established. The purpose of this study was to investigate the relationship between the renal shape, as measured by ultrasound, and the clinical characteristics in chronic kidney disease (CKD) patients.

Methods: The study included 121 CKD patients who had undergone kidney biopsy. The renal shape was defined by: (1) the renal shape index: renal length/(renal width + renal thickness) and (2) the renal width/length. IgA nephritis patients (excluding patients with diabetes), comprised the largest subgroup (n = 49) and were analyzed separately.

Results: The correlation analyses and two-sample Student's t test results showed that age, eGFR, BMI, cortex volume fraction measured by MRI (cortex volume/renal volume), percentage of global sclerosis, weight, sex, hypertension and diabetes were significantly correlated with the renal shape in both kidneys. In a stepwise multiple linear regression analysis, old age and high BMI were independently associated with plump kidney. As for the left renal shape index, low cortex volume fraction was also independently associated with plump kidney. In the IgA nephritis patient subgroup, the cortex volume fraction was the most significant factor contributing to the left renal shape index (r = 0.50, p < 0.01) and the width/length (r = -0.47, p < 0.01).

Conclusion: Age and BMI were stronger determinants of renal shape than renal function in CKD patients. The left renal cortex volume fraction was also an independent determinant and a more important factor in IgA nephritis patients.

Keywords: Chronic kidney disease; MRI; Renal cortex volume; Renal shape; Ultrasound.