Clinical Studies on Zinc Metabolism during Total Parenteral Nutrition as Related to Zinc Deficiency

Abstract

In 99 adult patients receiving controlled total parenteral nutrition (TPN), a study was made on the time course of concentrations of zinc in plasma, erythrocyte and urine in relation to the development of zinc deficiency. Zinc deficiency developed in 11 cases receiving TPN solutions not containing zinc. The plasma zinc level was significantly lower at the time of onset of zinc deficiency than in normal subjects, before the procedure of TPN, or at the time of symptomatic relief achieved by administration of zinc. The erythrocyte zinc level was slightly but not significantly lower at time of onset of zinc deficiency than in normal subjects, before TPN or at time of symptomatic relief. The urinary zinc level at time of onset of zinc deficiency was significantly lower than that in normal subjects or at the time of symptomatic relief but not significantly lower than that before TPN. A comparison between patients developing and those not developing zinc deficiency within 4 wk of the outset of TPN showed that only the plasma zinc level was significantly lower in the former than the latter group. The urinary zinc level also tended to be lower, although not significantly, in the former than the latter group but varied widely. No difference was present between the groups as to the erythrocyte zinc level. Zinc deficiency developed in none of those patients who had a plasma zinc level of 50 μg/dl or more but in five of 10 (50%) patients with less than 50 μg/dl and in all three with less than 30 μg/dl of zinc in plasma. Zinc deficiency was frequent in patients with benign gastrointestinal diseases, notably inflammatory bowel diseases. During the course of TPN with solutions not containing zinc a steady fall occurred only in plasma zinc level. Administration of in daily dose of 60 μmol (3.9 mg) was adequate to prevent plasma zinc level from falling and maintain it essentially within normal range. None of the patients receiving zinc in daily dose of 60 μmol (3.9 mg) developed sings or symptoms of zinc deficiency or showed an abnormally elevated plasma zinc level. (Journal of Parenteral and Enteral Nutrition 10:195-202, 1986)