A prospective study of serum copper and zinc levels in patients receiving total parenteral nutrition.

Weekly determinations of serum copper (Cu) and zinc (Zn) were made in eight adult patients receiving total parenteral nutrition (TPN) for 3 to 13 weeks. Serum Cu decreased in all eight patients. Five of eight patients had hypocupremia lasting at least 2 consecutive weeks and three of the five had Cu levels of 30 mug/dl or lower. Low levels of serum ceruloplasmin provided supportive evidence of Cu deficiency in the three patients with the lowest Cu levels. Two patients who had Cu less than or equal to 20 mug/dl demonstrated declines in hemoglobin which were probably due to Cu deficiency. The mean rate of decline in serum Cu was 10.8 mug/dl/week. After resumption of oral feedings in five patients, the mean rate of increase in Cu was 14 mug/dl/week. The sharpest rise in Cu was seen during the 2nd week after oral feedings were resumed in four of the five patients. Three of eight patients had serum Zn levels less than 70 mug/dl for at least 2 consecutive weeks. Serum Zn decreased at a mean rate of 6.6 mug/dl/week. There was a further decline in serum Zn in three of five patients in whom measurements were made after resumption of oral intake. Concentrations of Zn in TPN solutions varied between 0.63 and 1.0 mg/liter. Cu was undetectable in TPN solutions.