Diverse Renal Lesions in Obesity: Clinical and Pathologic Findings
Steven P Salvatore, Surya V Seshan. Weill Cornell Medical College, New York, NY
Background: Obesity related glomerulopathy (ORG) is a pathologic entity primarily mediated by hemodynamic changes, where glomerular hypertrophy, perihilar segmental sclerosis and variable foot process effacement are noted manifesting subnephrotic proteinuria in patients with obesity. Obese patients, at risk for developing ORG, may develop other glomerular, tubulointerstitial (TI) or vascular disease partly due to associated medical conditions. Herein we summarize the clinicopathologic characteristics of these renal lesions.
Design: Native kidney biopsies from 2000-2012 were retrospectively reviewed from patients with obesity, defined as body mass index greater than 30kg/m2. 32 cases were excluded including those with less than 5 glomeruli. Glomerular diameter was measured using a standard micrometer in 1-7 glomeruli (mean 4) in glomeruli cut through the hilum. Renal pathologic lesions detected by light, immunofluorescence, and electron microscopy were evaluated.
Results: Of 6702 total native kidney biopsies, 287 (4%) were obtained from obese patients. Proteinuria was the indication for biopsy in 93% of all obese patients, 11% had hematuria. Of the remaining 255 biopsies, 215 (84%) showed glomerulomegaly as defined by glomeruli greater than 180 μm in diameter, mean 224 μm +/- 34 mm. Renal lesions (other than secondary FSGS or glomerulomegaly alone) were present in 154 cases. Over 1/3 (56 cases) had diabetic nephropathy (DN) due to concomitant diabetes. The remainder had immune complex (IC) mediated disease 15% (6 IgA nephropathy, 10 lupus nephritis, 14 membranous glomerulonephritis (GN), 4 post infectious GN, 2 fibrillary GN, 1 C1q nephropathy, and 1 immune complex NOS), TI disease 4% (7 active interstitial nephritis, 2 acute tubular injury), thrombotic microangiopathy 2%, minimal change disease 3%, collapsing glomerulopathy 2%, thin glomerular basement membranes (GBM) isolated or with superimposed disease 5%, other non-specific changes 5%. Of the 27 hematuric patients, 48% (n=13) had either IgA nephropathy (6) or thin GBM (7). Proteinuria was highest in patients with idiopathic FSGS (mean 8g/24hrs) and IC GN (mean 7.4g/24hrs) and was subnephrotic in obesity-related FSGS (61%), glomerulomegaly-alone (82%), and TI diseases (80%). Presenting creatinine levels were highest in TI diseases (mean 8.4mg/dL) and DN (mean 2.5mg/dL) who were also older patients; DN (mean 54 yrs), TI diseases (mean 50 yrs), all others (mean 41yrs).
Conclusions: Diverse kidney pathology superimposed on ORG is present in obese patients with clinical renal disease. Renal biopsy is helpful for accurate diagnosis, prognosis, and treatment.
Category: Kidney (does not include tumors)
Monday, March 4, 2013 1:00 PM
Poster Session II # 244, Monday Afternoon