Excessive urinary oxalate excretion occurs in long-term TPN patients both with and without ileostomies.

OBJECTIVE

To determine if excessive oxalate and deficient citrate excretion were associated with TPN-associated nephropathy.

DESIGN

Crossectional cohort.

SETTING

Outpatient clinic.

SUBJECTS

Twenty-five patients (15 males, 10 females) aged 51 +/- 17 (mean +/- SD) years who had received home total parenteral nutrition (TPN) for 10 +/- 4 years. Fifteen 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 excretion.

RESULTS

The mean GFR was 68.1 +/- 34.5 ml/minute/1.73 m2 and did not differ between Groups A and B. The mean TRP was 65.0 +/- 32.2% for Group A and 80.5 +/- 16.0% for Group B. The difference was not statistically 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 differences were not statistically significant. Thirty-eight percent (38%) of patients with ileostomies and 78% of patients without ileostomies had excessive urinary oxalate excretion (> 40 mg/day). Fifteen percent (15%) of patients with ileostomies and 50% of patients without ileostomies had decreased urinary citrate excretion (< 140 mg/day).

CONCLUSIONS

Increased endogenous oxalate production may occur in patients receiving long-term TPN.