S H L Vale1, L D Leite2, C X Alves1, M M G Dantas1, J B S Costa3, J S Marchini4, M C França5, J Brandão-Neto6. 1. Postgraduate Program in Health Sciences, Universidade Federal do Rio Grande do Norte, Natal, Brazil. 2. Department of Nutrition, Universidade Federal do Rio Grande do Norte, Natal, Brazil. 3. Department of Chemical Engineering, Center for Industrial Technology, Universidade Federal do Rio Grande do Norte, Natal, Brazil. 4. Department of Internal Medicine, Universidade de São Paulo, Ribeirão Preto, Brazil. 5. Department of Statistics, Universidade Federal do Rio Grande do Norte, Natal, Brazil. 6. Department of Internal Medicine, Universidade Federal do Rio Grande do Norte, Natal, Brazil.
Abstract
BACKGROUND/ OBJECTIVES: Serum or tissue zinc concentrations are often used to assess body zinc status. However, all of these methods are relatively inaccurate. Thus, we investigated three different kinetic methods for the determination of zinc clearance to establish which of these could detect small changes in the body zinc status of children. SUBJECTS/ METHODS: Forty apparently healthy children were studied. Renal handling of zinc was investigated during intravenous zinc administration (0.06537 mg Zn/kg of body weight), both before and after oral zinc supplementation (5 mg Zn/day for 3 months). Three kinetic methods were used to determine zinc clearance: CZn-Formula A and CZn-Formula B were both used to calculate systemic clearance; the first is a general formula and the second is used for the specific analysis of a single-compartment model; CZn-Formula C is widely used in medical practices to analyze kinetic routine. RESULTS: Basal serum zinc values, which were within the reference range for healthy children, increased significantly after oral zinc supplementation. The three formulas used gave different results for zinc clearance both before and after oral zinc supplementation. CZn-Formula B showed a positive correlation with basal serum zinc concentration after oral supplementation (R2=0.1172, P=0.0306). In addition, CZn-Formula B (P=0.0002) was more effective than CZn-Formula A (P=0.6028) and CZn-Formula C (P=0.0732) in detecting small variations in body zinc status. CONCLUSIONS: All three of the formulas used are suitable for studying zinc kinetics; however, CZn-Formula B is particularly effective at detecting small changes in body zinc status in healthy children.
BACKGROUND/ OBJECTIVES: Serum or tissue zinc concentrations are often used to assess body zinc status. However, all of these methods are relatively inaccurate. Thus, we investigated three different kinetic methods for the determination of zinc clearance to establish which of these could detect small changes in the body zinc status of children. SUBJECTS/ METHODS: Forty apparently healthy children were studied. Renal handling of zinc was investigated during intravenous zinc administration (0.06537 mg Zn/kg of body weight), both before and after oral zinc supplementation (5 mg Zn/day for 3 months). Three kinetic methods were used to determine zinc clearance: CZn-Formula A and CZn-Formula B were both used to calculate systemic clearance; the first is a general formula and the second is used for the specific analysis of a single-compartment model; CZn-Formula C is widely used in medical practices to analyze kinetic routine. RESULTS: Basal serum zinc values, which were within the reference range for healthy children, increased significantly after oral zinc supplementation. The three formulas used gave different results for zinc clearance both before and after oral zinc supplementation. CZn-Formula B showed a positive correlation with basal serum zinc concentration after oral supplementation (R2=0.1172, P=0.0306). In addition, CZn-Formula B (P=0.0002) was more effective than CZn-Formula A (P=0.6028) and CZn-Formula C (P=0.0732) in detecting small variations in body zinc status. CONCLUSIONS: All three of the formulas used are suitable for studying zinc kinetics; however, CZn-Formula B is particularly effective at detecting small changes in body zinc status in healthy children.
Authors: Lúcia Dantas Leite; Erika Dantas de Medeiros Rocha; Maria das Graças Almeida; Adriana Augusto Rezende; Carlos Antônio Bruno da Silva; Mardone Cavalcante França; Júlio Sérgio Marchini; José Brandão-Neto Journal: J Am Coll Nutr Date: 2009-08 Impact factor: 3.169