Startseite Reference ranges for ionized calcium in plasma in Danish children aged 0 days to 3 years using laboratory registry data
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Reference ranges for ionized calcium in plasma in Danish children aged 0 days to 3 years using laboratory registry data

  • Anne-Sofie Allermann Faarvang ORCID logo EMAIL logo , Thomas S. Rosengren , Lars E. Pedersen , Pia B. Larsen und Esther A. Jensen
Veröffentlicht/Copyright: 12. August 2025
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Clinical Chemistry and Laboratory Medicine (CCLM)
Aus der Zeitschrift Clinical Chemistry and Laboratory Medicine (CCLM) Band 63 Heft 11

Abstract

Objectives

Measurement of ionized calcium is frequently used in the assessment of calcium metabolism. However, the utility of ionized calcium in young children can pose a challenge. In this study, we aimed at establishing novel accurate reference ranges for ionized calcium in plasma in a pediatric population.

Methods

All children aged 0–3 years who had ionized calcium measured in Region Zealand from 2012 to 2023 were included. Exclusion criteria included samples from intensive care units or nephrology departments and samples with pH under 7.2 or over 7.6. If a patient had repeated samples, only the last measurement per month for each child was used. In total, 20,516 ionized calcium measurements from 16,039 children were included. Based on these measurements, we established both pH corrected and non-corrected data sets.

Results

Data are described as median with 2.5th and 97.5th fractiles. Reference ranges were divided into age groups. We observed variation in reference ranges, especially in the first 10 days of life: 1.14–1.46 (pH corrected 1.13–1.43) mmol/L on day zero rising to 1.29–1.59 (pH corrected 1.27–1.55) mmol/L on day eight. After reaching peak levels on day eight, ionized calcium gradually decreased to 1.16–1.36 (pH corrected 1.17–1.35) mmol/L at 18–24 months of age.

Conclusions

We present novel reference ranges for ionized calcium in plasma. Results indicate a physiological rise in plasma ionized calcium after birth. After eight days, a steady decrease in plasma levels was seen before stabilizing at 18–24 months of age.

Keywords: calcium; ionized calcium; pediatric laboratory medicine; newborns; reference intervals
Corresponding author: Anne-Sofie Allermann Faarvang, Department of Clinical Biochemistry, Næstved Slagelse Ringsted Hospitals, Slagelse, Region Zealand, Denmark; Department of Clinical Biochemistry, Svendborg Hospital, Svendborg, Region of Southern Denmark, Denmark; and Department of Clinical Biochemistry, Slagelse Hospital, Fælledvej 11, 4200 Slagelse, Denmark, E-mail: .

Funding source: NSR Hospitals, Department of Clinical Chemistry

Acknowledgments

We would like to thank all study participants and technical staff for their invaluable contributions to this study.

  1. Research ethics: The local Institutional Review Board deemed the study exempt from review.

  2. Informed consent: Not applicable.

  3. Author contributions: All authors have accepted responsibility for the entire content of this manuscript and approved its submission.

  4. Use of Large Language Models, AI and Machine Learning Tools: None declared.

  5. Conflict of interest: The authors state no conflict of interest.

  6. Research funding: This project was funded by the Department of Clinical Biochemistry at NSR Hospitals, Region Zealand, Denmark.

  7. Data availability: Not applicable.

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Received: 2025-03-21
Accepted: 2025-07-30
Published Online: 2025-08-12
Published in Print: 2025-10-27

© 2025 Walter de Gruyter GmbH, Berlin/Boston

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https://doi.org/10.1515/cclm-2025-0353
Schlagwörter für diesen Artikel
calcium; ionized calcium; pediatric laboratory medicine; newborns; reference intervals

Artikel in diesem Heft

  1. Frontmatter
  2. Editorial
  3. Advancing diagnostic stewardship through claims-based utilization analysis: toward a system-wide vision of diagnostic excellence
  4. Review
  5. Biomarkers in body fluids and their detection techniques for human intestinal permeability assessment
  6. Mini Review
  7. Challenges of using natriuretic peptides to screen for the risk of developing heart failure in patients with diabetes: a report from the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) Committee on Clinical Applications of Cardiac Bio-Markers (C-CB)
  8. Opinion Papers
  9. Reference intervals in value-based laboratory medicine: a shift from single-point measurements to metabolic variation-based models
  10. Overview of laboratory diagnostics for immediate management of patients presenting to the emergency department with acute bleeding
  11. What Matters Most: an Age-Friendly approach to pathology and laboratory medicine
  12. No fault or negligence after an adverse analytical finding due to a contaminated supplement: mission impossible. Two examples involving trimetazidine
  13. General Clinical Chemistry and Laboratory Medicine
  14. Utilization analysis of laboratory tests using health insurance claims data: advancing nationwide diagnostic stewardship monitoring systems
  15. Evaluating large language models as clinical laboratory test recommenders in primary and emergency care: a crucial step in clinical decision making
  16. A novel corrective model based on red blood cells indices and haemolysis index enables accurate unhaemolysed potassium determination in haemolysed samples – Hemokalc project
  17. Validation of (self-collected) capillary blood using a topper collection system as alternative for venous sampling for 15 common clinical chemistry analytes
  18. Acoustophoresis-based blood sampling and plasma separation for potentially minimizing sampling-related blood loss
  19. Clinical validation of a liquid chromatography single quadrupole mass spectrometry (LC-MS) method using Waters Kairos™ Amino Acid Kit reagents
  20. Robustness of steroidomics-based machine learning for diagnosis of primary aldosteronism: a laboratory medicine perspective
  21. Investigation of the possible cause of over-estimation of human aldosterone in plasma, using a unique, non-synthetic human aldosterone-free matrix
  22. Performance of afternoon (16:00 h) serum cortisol for the diagnosis of Cushing’s syndrome
  23. MAGLUMI® Tacrolimus (CLIA) assay: analytical performances and comparison with LC-MS/MS and ARCHITECT Tacrolimus (CMIA) assay
  24. Assessment of 2023 ACR/EULAR antiphospholipid syndrome classification criteria in a Spanish cohort
  25. Comprehensive evaluation of antiphospholipid antibody testing methodologies in APS diagnosis: performance comparisons across assay systems and clinical subtypes
  26. Candidate Reference Measurement Procedures and Materials
  27. Exploring commutable materials for serum folate measurement: challenges in cross-method harmonization
  28. Reference Values and Biological Variations
  29. Reference ranges for ionized calcium in plasma in Danish children aged 0 days to 3 years using laboratory registry data
  30. A step forward in pediatric hemophagocytic lymphohistiocytosis and autoimmune disease: pediatric reference interval for serum soluble IL-2 receptor and soluble CD163
  31. Cancer Diagnostics
  32. Cellular expression of PD-1, PD-L1 and CTLA-4 in patients with JAK2V617F mutated myeloproliferative disorders
  33. Diabetes
  34. Serum N-glycans as independent predictors of the incidence of type 2 diabetes: a prospective investigation in the AEGIS cohort
  35. Infectious Diseases
  36. An assessment of molecular diagnosis of tuberculosis and multi-drug resistant tuberculosis testing and quality assessment: findings of an international survey
  37. Letters to the Editor
  38. Targeting low-value laboratory care
  39. Is time a significant factor in the release of potassium from lithium heparin plasma and serum?
  40. External quality assessment in resource-constrained laboratories: a survey of practices and perceptions in Nepal
  41. Is successfulness of platelet clump disaggregation by vortexing influenced by platelet measurement methods?
  42. Oligoclonal banding analysis: assessing plasma use and time interval requirements for paired CSF and blood
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