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...

These results suggest that glomerular hyperfiltration may lead to increased proximal tubular sodium reabsorption in the obese.

Advocates of health reform continue to pursue policies and tools that will make information about comparative costs and resource use available to consumers. Reformers expect that consumers will use the data to choose high-value providers-those who offer higher quality and lower prices-and thus contribute to the broader goal of controlling national health care spending. However, communicating this information effectively is more challenging than it might first appear. For example, consumers are more interested in the quality of health care than in its cost, and many perceive a low-cost provider to be substandard. In this study of 1,421 employees, we examined how different presentations of information affect the likelihood that consumers will make high-value choices. We found that a substantial minority of the respondents shied away from low-cost providers, and even consumers who pay a larger share of their health care costs themselves were likely to equate high cost with high quality. At the same time, we found that presenting cost data alongside easy-to-interpret quality information and highlighting high-value options improved the likelihood that consumers would choose those options. Reporting strategies that follow such a format will help consumers understand that a doctor who provides higher-quality care than other doctors does not necessarily cost more.

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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