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Pediatric ionized calcium reference intervals from archived radiometer data
Catherine L Omosule1, Vincent Holmes2, Cayden Jasek1
1Department of Pathology & Immunology, Washington University School of Medicine, St. Louis, MO, United States.
Insights
Establishing pediatric reference intervals for ionized calcium (iCa) is crucial. This study developed age-specific iCa ranges for children using archived data, revealing greater variability than in adults.
Area of Science:
- Pediatric clinical chemistry
- Biomarker reference intervals
- Calcium homeostasis
Background:
- Ionized calcium (iCa) is a vital measure of bioavailable calcium, particularly in pediatric care.
- Established pediatric iCa reference intervals (RI) are lacking, hindering accurate clinical interpretation.
- This study aimed to establish robust pediatric iCa RI using retrospective data.
Purpose of the Study:
- To retrospectively calculate age-specific reference intervals (RI) for ionized calcium (iCa) in a pediatric population.
- To utilize archived data from Radiometer instruments and apply stringent exclusion criteria for data integrity.
- To compare the developed RI with existing in-house ranges to validate the methodology.
Main Methods:
- Retrospective analysis of archived data from four Radiometer ABL800 FLEX blood gas analyzers.
- Application of exclusion criteria based on instrument data to ensure sample quality.
- Nonparametric rank order calculation of age-specific RI from over 5,000 pediatric individuals.
- Visual identification of inflection points and outlier removal for robust interval determination.
Main Results:
- Six age-specific iCa partitions were established for individuals aged 0 to 19 years.
- Pediatric iCa ranges were wider in early life, narrowing with age to approach adult levels by 2.5 years.
- Exclusion criteria effectively minimized the inclusion of results from acutely ill children, as suggested by sodium and creatinine data.
Conclusions:
- Pediatric ionized calcium concentrations exhibit greater variability than adult levels, influenced by developmental and nutritional factors.
- The study validates the feasibility and cost-effectiveness of using archived Radiometer analyzer data for establishing pediatric RI.
- This retrospective approach offers a practical alternative for RI development when prospective studies are unfeasible.
Background:
Measurement of ionized calcium (iCa) reflects bioavailable calcium and has significant utility in children. However, robust pediatric iCa reference intervals (RI) have not been well-established. In this study, we retrospectively calculated RI for iCa in a pediatric population by accessing archived data acquired on Radiometer instruments and applying stringent exclusion criteria.
Methods:
Data saved on 4 Radiometer ABL800 FLEX blood gas analyzers were queried. Exclusion criteria were applied based on information available from these instruments. iCa results were plotted and inflection points were visually identified. Following outlier removal and partition verification, age-specific RI were calculated using a nonparametric rank order approach from > 5,000 individuals. Finally, the stringency of the exclusion criteria was assessed by calculating RI from additional results in the dataset and comparing to existing in-house ranges.
Results:
Six age-specific iCa partitions were established from 0 to 19 years. Relative to adults, wider ranges for the central 95th percentile were observed early in life that progressively narrowed with increasing age and approached adult concentrations by 2.5 years. Analysis of concurrent data for sodium and creatinine in the dataset suggest the applied exclusion criteria reduced the likelihood of including results from acutely-ill children.
Conclusions:
Normal concentrations of iCa in children are more variable than adults. Observed differences may reflect the transition from maternally supplied calcium to nutritional sources, the maturation of calcium homeostatic mechanisms, and/or the need for calcium for growth/development. This study also demonstrates the feasibility and advantages of using data archived on Radiometer analyzers to establish pediatric RI. This approach enables rapid, cost-effective evaluation of large datasets and may be a feasible option when prospective or detailed retrospective analyses are not possible.
