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Serum alkaline phosphatase and serum zinc concentrations in preterm infants with rickets and fractures
W W Koo1, P Succop, K M Hambidge
1Department of Pediatrics, University of Cincinnati College of Medicine, Ohio.
Insights
Serum alkaline phosphatase (AP) and zinc levels were studied in preterm infants. Higher AP and zinc were observed in infants with rickets and fractures, but they were not directly related.
Area of Science:
- Biochemistry
- Pediatric Medicine
- Nutritional Science
Background:
- Preterm infants are at risk for nutritional deficiencies.
- Alkaline phosphatase (AP) and zinc play crucial roles in bone health.
- Longitudinal data on AP and zinc in this population are limited.
Purpose of the Study:
- To investigate longitudinal changes in serum zinc and AP activity in small preterm infants.
- To examine the relationship between serum AP activity and serum zinc concentrations.
- To compare these parameters in preterm infants with and without rickets and/or fractures (R/F).
Main Methods:
- Serial measurements of serum AP activity and serum zinc concentrations were performed at 3, 6, 9, and 12 months.
- The study included 72 preterm infants with a mean birth weight of 1000 g.
- Infants were categorized based on radiographic evidence of R/F.
Main Results:
- Infants with R/F showed significantly higher serum AP and zinc levels at 3 months compared to those without R/F.
- Serum AP concentrations decreased, and serum zinc concentrations increased over time, stabilizing after 6 months.
- No direct correlation was found between serum AP activity and serum zinc concentrations.
Conclusions:
- Elevated serum AP and zinc at diagnosis in preterm infants with R/F may indicate increased bone turnover and zinc release.
- The findings suggest a complex interplay between zinc, AP, and bone metabolism in preterm infants.
- Further research is warranted to elucidate the precise mechanisms involved.
Abstract:
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 mumol/L) concentrations were significantly higher at 3 months compared with infants in the non-R/F group (193 +/- 12 U/L and 9.6 +/- 0.3 mumol/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.