Influence of multivitamin regimen on urinary oxalate in home parenteral nutrition patients

High urinary oxalate levels have been associated with high ascorbic acid intakes. An alteration in the vitamin regimen for home parenteral nutrition (HPN) patients because of product discontinuation resulted in provision of 500 mg instead of 100 mg ascorbic acid per HPN day. This regimen was associated with high urinary oxalate levels.

To determine if a switch from a multivitamin regimen containing 500 mg to one containing 100 mg of ascorbic acid daily would reduce urinary oxalate levels.

A 24-hour urine collection for oxalate was analyzed before switching the vitamin regimen back to 100 mg ascorbic acid and repeated 2 months after the change. A paired t test was conducted to compare measurements at baseline and at 2 months.

Overall, 18 patients completed both phases of this observational study. The initial urinary oxalate of 517 +/- 63 micromol/day decreased to 425 +/- 47 micromol/day after 2 months (p = .05). However, after applying the exclusion criteria, only 6 patients could be included. The baseline urinary oxalate of 649 +/- 106 micromol/day decreased to 391 +/- 57 micromol/day after 2 months (p = .006).

A change in the parenteral regimen of HPN patients from 500 mg ascorbic acid to 100 mg ascorbic acid is associated with a decrease in urinary oxalate levels. This suggests that a moderate dose of parenteral ascorbic acid (100 mg/day) may limit urinary oxalate appearance in HPN patients.