Chronic dehydration may impair renal function in patients with chronic intestinal failure on long-term parenteral nutrition

Background & aims Renal impairment is a documented complication in long-term parenteral nutrition (LTPN) patients. However, the aetiologies have remained elusive. The aim of this study was to evaluate the impact of parenteral nutrition, digestive status, and hydration level on renal function in LTPN patients. Methods In a prospective study of 40 LTPN patients, renal function and hydration level were assessed by measurement of inulin and creatinine clearances, plasma creatinine, urea, aldosterone and renin and urinary sodium/potassium ratio. Patients were assigned to one of two groups according to their inulin clearance (normal=Group 1, 20% decrease or more=Group 2). Results Of the patients, 52.5% (21/40) had a decrease in glomerular filtration rate (−38±15%), with age taken into consideration. Patient characteristics, parenteral nutrition composition or duration and intestinal status were not different between the two groups. Urologic or nephrologic diseases were more frequent in Group 2 patients. Moreover, in Group 2 patients, a urinary sodium/potassium excretion ratio of less than 1 in 8/21 patients and plasma renin (316±298 vs. 86±53% of normal value) and aldosterone (291±464 vs. 58±36 pmol/l) that were significantly higher than in Group 1 patients suggested a hypovolemic component. Conclusion Decreased renal function is frequent (52.5%) in LTPN patients. A volemic component was associated in more than 70% of them. An elevation of serum creatinine or an inversion of the urinary Na/K ratio requires an evaluation of hydration equilibration and an oral rehydration and a modification in parenteral nutrition formulation.