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November 1989

Serum Alkaline Phosphatase and Serum Zinc Concentrations in Preterm Infants With Rickets and Fractures

Author Affiliations

From the Departments of Pediatrics and Environmental Health (Division of Biostatistics), University of Cincinnati (Ohio) College of Medicine (Drs Koo and Succop); the Children's Hospital Research Foundation, Cincinnati (Dr Koo); and the University of Colorado, Denver (Dr Hambidge). Dr Koo is now with the University of Alberta Hospitals, Edmonton, Canada.

Am J Dis Child. 1989;143(11):1342-1345. doi:10.1001/archpedi.1989.02150230100032

• This study aimed to determine the longitudinal changes in serum zinc concentrations and the relationship between serum alkaline phosphatase (AP) activity and serum zinc concentrations in small preterm infants. The total serum AP and serum zinc concentrations were determined serially at 3,6, 9, and 12 months in 72 infants with mean (±SEM) birth weights of 1000±29 g and gestational ages of 28.6 ± 0.3 weeks. Twenty-four of 72 infants had radiographic evidence of rickets and/or fractures (R/F). In infants with R/F, group mean (±SEM) serum AP (371 ±42 U/L) and serum zinc (12.5±1.0 μmol/L) concentrations were significantly higher at 3 months compared with infants in the non-R/F group (193±12 U/L and 9.6±0.3μmol/L, respectively). During the study, the serum AP concentrations decreased, and the serum zinc concentrations increased; both stabilized after 6 months. The serum AP concentrations were not related to the serum zinc concentrations. We speculate that in preterm infants, an increased bone turnover and a release of tissue (bone) zinc may contribute to the higher group mean serum AP and serum zinc concentrations at the time of diagnoses in infants with R/F compared with those infants without R/F.

(AJDC. 1989;143:1342-1345)