Abstract. Severe obesity is associated with increased renal plasma flow (RPF) and glomerular filtration rate (GFR). The aim of the present study was to examine whether weight loss may reverse glomerular dysfunction in obese subjects without overt renal disease. Renal glomerular function was studied in eight subjects with severe obesity (body mass index [BMI] 48.0 Ϯ 2.4) before and after weight loss. Nine healthy subjects served as controls. GFR and RPF were determined by measuring inulin and PAH clearance. In the obese group, GFR (145 Ϯ 14 ml/min) and RPF (803 Ϯ 39 ml/min) exceeded the control value by 61% (90 Ϯ 5 ml/min, P ϭ 0.001) and 32% (610 Ϯ 41 ml/min, P Ͻ 0.005), respectively. Consequently, filtration fraction was increased.Mean arterial pressure, although normal, was higher than in the control group (101 Ϯ 4 versus 86 Ϯ 2 mmHg, P Ͻ 0.01). After weight loss, BMI decreased by 32 Ϯ 4%, to 32.1 Ϯ 1.5 (P ϭ 0.001). GFR and RPF decreased to 110 Ϯ 7 ml/min (P ϭ 0.01) and 698 Ϯ 42 ml/min (P Ͻ 0.02), respectively. Albumin excretion rate decreased from 16 g/min (range, 4 to 152 g/min) to 5 g/min (range, 3 to 37 g/min) (P Ͻ 0.01). Fractional clearance of albumin decreased from 3.2 ϫ 10 Ϫ6 (range, 1.1 to 23 ϫ 10Ϫ6 (range, 0.5 to 6.8 ϫ 10 Ϫ6) (P Ͻ 0.02). This study shows that obesity-related glomerular hyperfiltration ameliorates after weight loss. The improvement in hyperfiltration may prevent the development of overt obesity-related glomerulopathy.Severe obesity is associated in with increased systemic arterial pressure (1), high renal plasma flow (2-4), increased GFR (2,5), and enhanced albumin excretion rate (6,7). We have previously studied glomerular hemodynamics in patients with severe obesity by measuring the fractional clearances of dextrans of broad size distribution (8). Analysis of the dextran sieving data, using a theoretical model of macromolecule transport through a heteroporous membrane, showed that the glomerular capillary bed was subjected to an elevated transcapillary hydraustatic pressure gradient resulting in hyperfiltration. In addition to these physiologic abnormalities, many reports have associated obesity with the occurrence of nephrotic syndrome and renal failure (9 -19). Obesity-related glomerulopathy was recently defined morphologically as glomerulomegaly with or without focal segmental glomerulosclerosis (20). Obesity may also accelerate the course of idiopathic glomerular disease, such as IgA glomerulopathy (21). The prevalence of obesity-related glomerulopathy, which may lead to end-stage renal disease, has increased tenfold over the last 15 yr as a consequence of "the spread of the obesity epidemic" (22). Although a cause-and-effect relationship between the obesityassociated glomerular hyperfunction and the development of nephrotic syndrome and renal failure has not been demonstrated, experimental and clinical data suggest that hyperfiltration and glomerulomegaly may lead to glomerular damage. Therefore, reducing glomerular hyperfiltration may provide a way to prevent or delay the deve...

Abstract. Large dialysate volumes are often required to increase solute clearance for peritoneal dialysis patients. The resulting increase in solute clearance might be attributable to an increased plasma-to-dialysate concentration gradient and/or to an increased effective peritoneal surface area. One of the factors affecting the latter is the peritoneal surface area in contact with dialysate (PSA-CD). The aim of this study was to estimate the change in PSA-CD after a 50% increase in the instilled dialysate volume for patients undergoing peritoneal dialysis. PSA-CD was estimated by using a method applying stereologic techniques to computed tomographic (CT) scans of the peritoneal space. The peritoneal cavity of 10 peritoneal dialysis patients was filled with a solution containing dialysate, half-isotonic saline solution, and contrast medium. Peritoneal function tests and CT scanning of the abdomen were performed twice for each patient (with an interval of 1 wk), after instillation of a 2-or 3-L solution. Scanning of thin helical CT sections was performed, and 36 random sections of the abdomen were obtained after reconstruction. A grid was superimposed on the sections. The surface area was estimated by using stereologic methods.

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Background: Elevated phosphorus (P) and calcium (Ca)-P product (Ca × P) are associated with vascular calcification and cardiovascular disease (CVD) morbidity and CVD and all-cause mortality. Objectives: This study examined the effect of sevelamer hydrochloride exposure (regardless of calcium carbonate exposure) on carotid and femoral intima media thickness (IMT), reliable surrogate measures of prospective intimal thickening, in end-stage renal disease patients on maintenance hemodialysis. Methods: The present cross-sectional study is nested in the Sevelamer hydrochloride and ultrasound-measured femoral and carotid intima media thickness progression in end-stage renal disease (SUMMER) clinical trial. Carotid and femoral arteries were visualized in B-mode ultrasonography. Log-transformed IMT was compared by sevelamer hydrochloride exposure and modeled using multiple linear regression. Results: Forty-five subjects were exposed to sevelamer hydrochloride and 130 were not. Exposed subjects had significantly lower carotid IMT, an association which persisted in the multiple linear regression model even after controlling for potentially confounding variables including serum Ca, history of CVD and body weight. Exposed subjects had lower low-density lipoprotein cholesterol levels and significantly higher parathyroid hormone, but no differences in P, Ca and Ca × P. Conclusions: Sevelamer hydrochloride was associated with lower carotid IMT. This association may be mediated through reduction in Ca load, low-density lipoprotein cholesterol lowering or some other pleiotropic effect.