Serum zinc and copper in people with COVID-19 and zinc supplementation in parenteral nutrition

OBJECTIVES: Zinc and copper are important to protect cells from oxidative stress and to enhance immunity. An association between low zinc levels and the severity of acute respiratory distress syndrome has been shown for people with COVID-19. We aimed to study serum zinc and copper concentrations in people with severe COVID-19 and zinc supplementation in parenteral nutrition (PN). METHODS: Thirty-five people with COVID-19 in need of PN were studied in a retrospective design. Serum samples were collected at three time points: at the start of PN, between 3 and 7 d after, and at the end of PN. RESULTS: Participants were on PN for a mean of 14 d, with a mean (± SD) daily supplemental zinc of 14.8 ± 3.7 mg/d. Serum zinc increased during PN administration from 98.8 ± 22.8 to 114.1 ± 23.3 µg/dL (Wilks’ λ = 0.751, F = 5.459, P = 0.009). Conversely, serum copper did not vary from baseline (107.9 ± 34.2 µg/dL) to the end of the study (104.5 ± 37.4 µg/dL, Wilks’ λ = 0.919, F = 1.453, P = 0.248). Serum zinc within the first week after starting PN and at the end of PN inversely correlated with total hospital stay (r = −0.413, P = 0.014, and r = −0.386, P = 0.022, respectively). Participants in critical condition presented lower serum copper (z = 2.615, P = 0.007). Mortality was not associated with supplemental zinc or with serum zinc or copper concentrations at any time of the study (P > 0.1 for all analyses). CONCLUSIONS: Serum zinc concentrations during PN support were inversely associated with length of hospital stay but not with mortality. Serum copper concentrations were lower in participants in critical condition but not associated with prognosis.