Does infusion time affect the retention of parenteral trace elements?

When readymade parenteral nutrition in multi-chamber bags is supplied without vitamins and minerals, these have to be added or given separately. Separate rapid infusion has logistical advantages but has been claimed to saturate tissue mechanisms, potentially increasing urine micronutrient losses. The present study compared urinary losses after fast (1 h) v. slow (10 h) trace elements infusion. The study enrolled thirty-nine consecutive patients who were starting parenteral nutrition postoperatively. One day's dose of a complete intravenous micronutrient product was infused over 1 h and over 10 h, in random order, with a washout day after each infusion day. Urinary Zn, Mn, Se, Cr, Cu and Fe losses were measured by 24-h urine collection, recorded for each infusion day and subsequent washout day. For Zn, a dose of 100 µmol was given, and total urinary loss over the next 2 d was mean 40·6 (sd 23·8) µmol after the fast (1 h) infusion v. 33·4 (sd 25·4) µmol after the slow (10 h) infusion, that is, 7 % more of the 1-d dose was lost after fast infusion (P = 0·01). For Mn, after a dose of 1000 nmol, losses were 9·8 (sd 23·9) nmol after the fast infusion v. 22·1 (sd 47·2) nmol after the slow infusion, that is, 1 % more of the 1-d dose was lost after slow infusion (P = 0·04). There were no other significant differences: after 1 µmol Se, the losses were 1·5 (sd 0·6) µmol fast v. 1·3 (sd 0·5) µmol slow; after 200 nmol Cr, 257 (sd 92) µmol fast v. 246 (sd 107) nmol slow; after 8 µmol Cu, 1·6 (sd 1·4) µmol fast v. 1·5 (sd 1·3) µmol slow; and after 20 µmol Fe, 0·6 (sd 1·1) µmol fast v. 0·8 (sd 1·6) µmol slow (P > 0·05 for all). Overall, trace element retention appears to be minimally affected by infusion time.