Latent copper deficiency in patients receiving low-copper enteral nutrition for a prolonged period

Background: Copper deficiency has been reported in patients supported with long-term enteral nutrition. Occasionally, this leads to anemia and leukopenia. There is no detailed report relating to the onset time of copper deficiency and how the symptoms develop. This report describes the relation between copper deficiency symptoms and duration of enteral nutrition. Methods: The study included 55 patients, with 82 measurements, at the neurologic ward of Nagoya Daini Red Cross Hospital. The mean age was 71 ± 11 years. The daily average dosage of energy was 938 kcal/d. A commercial nutrient for enteral administration that contains 0.13 mg/1000 mL copper was used. Baseline measures on individual patients were taken every month. Blood was collected at 8 AM before and after the start of enteral nutrition. Levels of copper, zinc, ceruloplasmin, hemoglobin, and white blood cells were measured. Results: The serum level of copper in the patients was 94.0-181.0 μg/dL before the start of enteral nutrition. The level of serum copper remained within the normal range for about 3 months. The level of serum copper in the patients decreased gradually and was less than the normal level after 3 months, with the exception of 1 patient. The serum level of copper in the patients was 3.0-123.0 μg/dL 3 months after the start of enteral nutrition. The levels of serum copper were below normal in 25 cases out of 82 measurements. However, the number of patients with symptoms of copper deficiency was only 2. Copper deficiency symptoms appeared at 41 and 77 months, the average being 59 months. Conclusions: Almost all patients showed a latent copper deficiency about 3 months after the start of ente0ral nutrition. However, only a few patients developed overt symptoms of copper deficiency.