Obesity-Related Glomerulopathy in China: A Case Series of 90 Patients

Abstract

The epidemic of obesity has been paralleled by an increase in the incidence of chronic kidney disease. However, epidemiological data for obesity-related glomerulopathy (ORG) from developing countries, including China, are very limited. Case series. ORG defined as body mass index (BMI) of 28.0 kg/m(2) or greater; urinary protein excretion of 0.4 g/24 h or greater, and glomerulomegaly (glomerular volume > 3.27 x 10(6) microm(3)) with or without focal segmental glomerulosclerosis (FSGS). 10,093 renal biopsy samples from patients obtained from February 2002 to November 2006 at the Research Institute of Nephrology, Nanjing University School of Medicine, China. Obesity defined as a BMI of 28.0 kg/m(2) or greater. Subjects were divided into 3 groups: mild-obesity group with BMI of 28.0 to less than 30 kg/m(2), moderate-obesity group with BMI of 30 to less than 35 kg/m(2), and severe-obesity group with BMI of 35 kg/m(2) or greater. Clinicoepidemiological and histopathologic characteristics of patients with ORG at the time of biopsy were described separately. ORG was observed in 90 biopsy specimens (0.89%); frequency increased from 0.62% to 1.0% during the last 5 years (P = 0.02). Mean age was 37.5 +/- 9.3 (SD) years, 67% were men, mean BMI was 31.2 +/- 3.3 kg/m(2), waist circumference was 103 cm (range, 89.4 to 124 cm) in men and 96.5 cm (range, 88.5 to 113 cm) in women, waist-hip ratio was 0.95 +/- 0.07, and 100% had visceral obesity. Of the total, 49%, 37%, and 14% had mild, moderate, and severe obesity, respectively. Mean urinary protein excretion of subjects was 1.48 +/- 1.2 g/24 h; 51%, 39%, and 10% had proteinuria with protein of 0.4 to 1.0, 1.0 to 3.5, and greater than 3.5 g/d, respectively. Mean measured creatinine clearance (Ccr) was 109 +/- 32.2 mL/min/1.73 m(2), with 42%, 36%, and 22% with a Ccr greater than 120, 90 to 120, and less than 90 mL/min/1.73 m(2), respectively. Glucose dysmetabolism, insulin resistance, dyslipidemia, and hypertension were observed in 77%, 88%, 76%, and 63% of patients, respectively. FSGS was observed in 70%. Mean foot-process width was 534 +/- 176 nm. Foot-process fusion was seen in 36% of patients. Greater BMI was associated with greater proteinuria (P < 0.02), greater Ccr (P < 0.03), and greater foot-process width (P < 0.04). Inability to compute prevalence or incidence from case series. BMI was calculated at time of renal biopsy. Most patients with ORG had mild obesity, visceral obesity, minor proteinuria, preserved Ccr, and FSGS.