EXCESSIVE URINARY OXALATE EXCRETION OCCURS IN LONG-TERM TPN PATIENTS BOTH WITH AND WITHOUT ILEOSTOMIES

Objective: To determine if excessive oxalate and deficient citrate exc retion were associated with TPN-associated nephropathy. Design: Crosse ctional cohort. Setting: Outpatient clinic. Subjects: Twenty-five pati ents (15 males, 10 females) aged 51 +/- 17 (mean +/- SD) years who had received home total parenteral nutrition (TPN) for 10 +/- 4 years. Fi fteen subjects had ileostomies (Group A) and 10 had functional colons (Group B). Outcome measures: Glomerular filtration rate (GFR), tubular reabsorption of phosphate (TRP), urinary oxalate and citrate excretio n. Results: The mean GFR was 68.1 +/- 34.5 ml/minute/1.73 m(2) and did not differ between Groups A and B. The mean TRP was 65.0 +/- 32.2% fo r Group A and 80.5 +/- 16.0% for Group B. The difference was not stati stically significant. Urinary oxalate and citrate excretion were 40.2 +/- 30.2 and 324.4 +/- 239.0 mg/day respectively for Group A, and 63.2 +/- 34.2 and 474.8 +/- 936.3 respectively for Group B. The difference s were not statistically significant. Thirty-eight percent (38%) of pa tients with ileostomies and 78% of patients without ileostomies had ex cessive urinary oxalate excretion (>40 mg/day). Fifteen percent (15%) of patients with ileostomies and 50% of patients without ileostomies h ad decreased urinary citrate excretion (<140 mg/day). Conclusions: Inc reased endogenous oxalate production may occur in patients receiving l ong-term TPN.