Zinc homeostasis in pediatric critical illness

Objective: We explored the hypothesis that marked decline in plasma zinc concentrations among critically ill children is related to shifts in metallothionein expression and inflammation. Design: Prospective pilot study. Setting: Intensive care unit of tertiary care children's hospital. Patients: All children (18 yrs) with unadjusted Pediatric Risk of Mortality III score >5 or at least one organ failure admitted to the pediatric intensive care unit from March through August 2006 were eligible for enrollment. Interventions: After consent, blood samples were collected on days 1 and 3 of illness and analyzed for serum chemistries, plasma zinc and copper levels, metallothionein isoform expression, and cytokine levels. Measurements and Main Results: Twenty patients were enrolled, with median age of 2.9 yrs (interquartile range, 0.7-10.1). Male to female ratio was 1.21. All patients had low zinc levels (mean, 0.43; range, 0.26-0.66 mu g/dL) on day 1 of pediatric intensive care unit admission, and remained low (mean, 0.51; range, 0.26-0.81 mu g/dL) on day 3, even when corrected for hypoalbuminemia. In comparison, serum copper levels were normal. On day 1, there was a positive correlation between zinc levels and expression of MT-1 A (p < 0.01), MT-1 G (p = 0.02), and MT-1H (p = 0.03). Plasma zinc levels correlated inversely with C-reactive protein levels (r = -.75, p = 0.01) and interleukin-6 levels (r = -.53, p = 0.04) on day 3. On day 3, patients with two or more organ failures had significantly lower plasma zinc concentrations compared with patients with :51 organ failure (p = 0.03). Conclusions., Plasma zinc concentrations are low in critically ill children. Plasma zinc correlated with measures of inflammation (C-reactive protein and interieukin-6) on day 3; low plasma zinc concentrations were associated with the degree of organ failure on day 3. These data serve as the basis for a larger study of shifts in plasma zinc concentrations in critically children to potentially identify patients who might benefit from zinc supplementation. (Pediatr Crit Care Med 21309; 10:29-34)