Clinicopathological Influence of Obesity in IgA Nephropathy: Comparative Study of 74 Patients

Abstract

The pathological role of obesity has rarely been studied in primary glomerular diseases. The purpose of this study is to examine the clinicopathological influence of obesity in IgA nephropathy (IgAN). 74 patients with IgA nephropathy in our institution from October 2000 to January 2004 were retrospectively divided into two groups according to body mass index (BMI): the non-obese group (group N) with BMI < 25 kg/m(2), and the obese group (group O) with BMI > or = 25 kg/m(2). There were 50 patients in group N and 24 patients in group O. Clinical analysis showed no significant difference between these two groups in blood pressure, serum cholesterol, creatinine clearances or grade of hematuria. However, urinary protein excretion and serum creatinine were significantly greater in group O than in group N. Although semiquantitative analysis of light-microscopical findings showed no significant differences in the severity of mesangial proliferation, matrix expansion, glomerulosclerosis or crescent formation, image analysis showed that total glomerular area and tuft area were significantly larger in group O. In addition, ultrastructural study revealed significantly higher glomerular basement membrane thickness in group O. 62 patients (46 patients, group N; 16 patients, group O) were followed in our institution for one year. Urinary protein was significantly decreased only in patients who received steroid in both groups. Although administration of ACE inhibitor or ARB tended to decrease urinary protein in group O, the change was not statistically significant. Our findings indicate that obesity may accelerate the increase of proteinuria in IgAN through ultrastructural modification of the glomerular basement membrane.

Pathological influence of obesity on renal structural changes in chronic kidney disease

“…Ultrastructural study of IgAN with obesity has seldom reported. Tanaka et al reported that obese IgAN patients showed greater GBM thickening and larger total glomerular tuft areas, compared with the lean IgAN patients [16]. Our data also showed significantly larger glomerular size in obese IgAN than non-obese IgAN.…”

“…A few studies of obesity and IgAN have been reported [4,16]. When obesity accompanies IgAN, the pathological changes were more severe and proteinuria was grater [4].…”

Long-Term Outcomes of IgA Nephropathy Presenting with Minimal or No Proteinuria

“…These results are in agreement with many observational and prospective radomized controlled trials that have emphasized the crucial role of proteinuria in the long-term outcome of the disease. [1][2][3][4][5][6][7][8][19][20][21][22] Although overweight and obesity have been identified as independent risk factors for chronic renal failure and increasing proteinuria in IgAN, 23,24 we found no influences of BMI on primary or secondary outcomes by univariate or multivariate analysis. This finding would suggest that the harmful effect of obesity on IgAN is restricted to more severe types of the disease.…”

Current Therapy for IgA Nephropathy

“…10 This is expected since loss of renal function likely identifies the subgroup of IgAN patients who are already progressive. Finally, renal prognosis is worse in obese IgAN patients, 13,14 possibly related to superimposed obesity-related renal changes. 15 Nonsurgical weight loss can indeed lead to a reduction of proteinuria.…”