title: Plasma zinc is an insensitive predictor of zinc status: use of plasma zinc in children with sickle cell disease.
abstract: BACKGROUND
  This study was designed to explore the use of plasma zinc in determining zinc deficiency in children with sickle cell disease-SS (SCD-SS) as indicated by a growth response to zinc supplementation.
  
  
  METHODS
  Fasting plasma zinc was assessed in children with SCD-SS (ages 4 to 10 years) who were randomly assigned to receive 10 mg zinc/d in cherry syrup (zinc) or cherry syrup alone (placebo) for 12 months. Evaluations for growth, dietary intake, and other biochemical parameters were made at baseline and 3, 6, and 12 months. Longitudinal mixed effects analysis evaluated differences between groups over 12 months.
  
  
  RESULTS
  A total of 38 prepubertal children (20 male and 18 female; 18 zinc and 20 placebo) completed the study (7.1 +/- 1.7 years old). At baseline, plasma zinc was low (< or = 70 microg/dL) in 7 male subjects. Despite the significant increase in height over 12 months (+0.7 cm) with zinc supplementation (p = .019), plasma zinc did not change over the 12 months of study, and there was no association between plasma zinc and linear growth. Those children with low plasma zinc who received zinc supplementation showed improved linear growth.
  
  
  CONCLUSIONS
  These findings suggest that plasma zinc is an insensitive indicator of zinc status in children with SCD-SS. Children with low plasma zinc will benefit from zinc supplementation. However, some children with normal plasma zinc and poor growth may also have growth-limiting zinc deficiency and exhibit a growth response to zinc supplementation. Although this study focused on children with SCD-SS, results may be generalized to other pediatric clinical illnesses where nutrition-related growth failure is investigated.
authors.affiliation: Department of Hematology, Children's Hospital and Research Center at Oakland, 747 52nd Street, Oakland, California 94609, USA. efung@mail.cho.org
authors.forename: Ellen B
authors.initials: EB
authors.lastname: Fung
authors.forename: Deborah A
authors.initials: DA
authors.lastname: Kawchak
authors.forename: Babette S
authors.initials: BS
authors.lastname: Zemel
authors.forename: Kwaku
authors.initials: K
authors.lastname: Ohene-Frempong
authors.forename: Virginia A
authors.initials: VA
authors.lastname: Stallings