Nitrogen Balance in Parenteral Nutrition

To the Editor.—We were interested to read "Nitrogen Balance in Postoperative Patients Receiving Parenteral Nutrition" by Van Way et al (Arch Surg 110:272, 1975). We have had considerable experience in the assessment of intravenous nutritional regimens in patients undergoing elective abdominal surgery, and we agree that increasing calorie and nitrogen intake improves nitrogen sparing, but at no time, using similar intakes, have we produced positive nitrogen balance.

In one of our studies, five patients receiving 0.23 gm/day of nitrogen per kilogram of body weight and 51 kcal/day per kilogram of body weight had a daily nitrogen balance of −3.48±0.98 gm (mean ± SE) and positive balance was only achieved when oral feeding recommenced. The differences between our observations and those of Van Way et al may reflect variations in the method of administration or the technique of collection and measurement, a point that is emphasized by considering our respective control