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Differential solute clearances were used to characterize glomerular function in 12 nondiabetic subjects with severe obesity (body mass index >38). Nine healthy subjects served as the control group. In the obese group, glomerular filtration rate (GFR) and renal plasma flow (RPF) exceeded the control value by 51 and 31%, respectively. Consequently, filtration fraction increased. The augmented RPF suggested a state of renal vasodilatation involving, mainly or solely, the afferent arteriole. Albumin excretion rate and fractional albumin clearance increased by 89 and 78%, respectively. Oral glucose tolerance tests were suggestive of insulin resistance. Insulin resistance was positively correlated with GFR (r = 0.88, P<0.001) and RPF (r = 0.72, P <0.001). Mean arterial pressure was higher than in the control group. Fractional clearances of dextrans of broad size distribution tended to be lowered. The determinants of the GFR were estimated qualitatively by using a theoretical model of dextran transport through a heteroporous membrane. This analysis suggests that the high GFR in very obese subjects may be the result of an increase in transcapillary hydraulic pressure difference (DeltaP). An abnormal transmission of increased arterial pressure to the glomerular capillaries through a dilated afferent arteriole could account for the augmentation in DeltaP.

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...

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Antibiotic catheter lock solutions reduce catheter-related bloodstream infections, with a number needed to treat of 4 patients (95% CI, 4-5), and catheter removal rates in patients undergoing hemodialysis. The use of antibiotic catheter lock solutions should be considered in routine clinical practice in conjunction with other prevention modalities.

Our review shows that patients on hemodialysis therapy have better Hb level response when treated with IV iron. For patients with CKD, this effect is small.

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