A high peritoneal large pore fluid flux causes hypoalbuminaemia and is a risk factor for death in peritoneal dialysis patients

Background. Hypoalbuminaemia is common in peritoneal dialysis (PD) patients and has an associated high mortality. An excess morbidity and mortality has previously been found in patients with high peritoneal transport. A high peritoneal large pore fluid flux (Jv_L) results in increased peritoneal loss of protein that possibly contributes to patient morbidity. Alternatively, hypoalbuminaemia and high transport status could be just a marker of capillary pathology associated with atherosclerotic comorbidity. Methods. Peritoneal dialys is capacity computer modelling of peritoneal transport, based on Rippe's three-pore model, was performed to measure Jv_L in 155 incident PD patients 2-4 weeks after PD initiation. Patient clinical and biochemical status was determined -6, -3, -1, 1 and 6 months after PD initiation, and every 6 months thereafter. Jv_L was redetermined in prevalent patients 2 and 4 years after PD initiation. Results. Jv_L was 0.106±0.056 ml/min/1.73 m² (median 0.094, interquartile range 0.068-0.128). It was correlated to age*** (*P<0.05; **P<0.01; ***P<0.001) (20-30 years 0.079±0.04; 70 years 0.121±0.071), but not to gender. No correlation to diabetic or preexisting renal replacement therapy was seen, but patients with atherosclerosis had higher Jv_L (0.123±0.06 vs 0.100±0.056*) as had patients with other systemic disease (0.121±0.68 vs 0.100±0.051*). Jv_L was positively correlated to area parameter (r = 0.41***), and negatively correlated to plasma albumin (-0.36***). Patients were divided into three equal groups: group 1, Jv_L <0.075 ml/min/1.73 m²; group 2, 0.075-0.11; group 3: >0.11. There was no difference between the groups in p-albumin prior to PD. Immediately after PD start, differences between the three groups appeared (1 month p-albumin: (μmol/l) group 1, 548±83; group 2, 533±86; group 3, 497±78**), and persisted for up to 6 years. No significant change in Jv_L was seen at 2 and 4 years. Patients with significant albuminuria also had hypoalbuminaemia (<1 g/day: 546±81μmol/l; >2 g/day: 503±54μmol/l). Intermittent PD ameliorated the effect of Jv_L on albumin losses and clearance. Mortality was increased significantly with raised Jv_L, independently of age (2 year mortality: Group 1, 10%, group 3, 32%*). There was no overall effect on technique survival, but hypoalbuminaemic group 3 patients had a higher failure rate*. Conclusion. Jv_L is related to hypoalbuminaemia and mortality after PD initiation. A high Jv_L seems to be a marker of preexisting vascular pathology, and to cause hypoalbuminaemia after PD initiation. It is suggested that peritoneal albumin loss can have an identical pathogenic effect as urinary albumin loss, by causing an iatrogenic 'nephrotic' syndrome.