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Calcium state estimation by total calcium: the evidence to end the never-ending story

  • Jean-David Pekar , Guillaume Grzych EMAIL logo , Gatien Durand , Joël Haas , Arnaud Lionet , Thierry Brousseau , François Glowacki and Patrice Maboudou
Published/Copyright: September 2, 2019
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Clinical Chemistry and Laboratory Medicine (CCLM)
From the journal Clinical Chemistry and Laboratory Medicine (CCLM) Volume 58 Issue 2

Abstract

Background

Total blood calcium (TCa) is routinely used to diagnose and manage mineral and bone metabolism disorders. Numerous laboratories adjust TCa by albumin, though literature suggests there are some limits to this approach. Here we report a large retrospective study on agreement rate between ionized calcium (iCa) measurement and TCa or albumin-adjusted calcium measurements.

Methods

We retrospectively selected 5055 samples with simultaneous measurements of iCa, TCa, albumin and pH. We subgrouped our patients according to their estimated glomerular filtration rate (eGFR), albumin levels and pH. We analyzed each patient’s calcium state with iCa as reference to determine agreement rate with TCa and albumin-adjusted calcium using Payne, Clase, Jain and Ridefelt formulas.

Results

The Payne formula performed poorly in patients with abnormal albumin, eGFR or pH levels. In patients with low albumin levels or blood pH disorders, Payne-adjusted calcium may overestimate the calcium state in up to 80% of cases. Similarly, TCa has better agreement with iCa in the case of hypoalbuminemia, but performed similarly to the Payne formula in patients with physiological albumin levels. The global agreement rate for Clase, Jain and Ridefelt formulas suggests significant improvement compared to Payne calcium adjustment but no significant improvement compared to TCa.

Conclusions

Total and albumin-adjusted calcium measurement leads to a misclassification of calcium status. Moreover, accurate calcium state determination depends on blood pH levels, whose measurement requires the same pre-analytical restrictions as iCa measurement. We propose that iCa should instead become the reference method to determine the real calcium state.

Keywords: acid-base disorder; albumin-adjusted calcium; ionized calcium; mineral and bone metabolism disorders; Payne formula; total calcium
Corresponding author: Dr. Guillaume Grzych, Centre de Biologie Pathologie, Laboratoire d’Hormonologie, Métabolisme-Nutrition, Oncologie, rue du Pr J. Leclercq, CHU Lille, F-59000 Lille, France; and Université de Lille, INSERM UMR-1011, Lille, France, Phone: +33(0)3.20.44.5454

  1. Author contributions: J.D.P., G.G., A.L., F.G. and P.M. designed the study; J.D.P. and G.D. collected the data; G.D. and G.G. analyzed the data; J.D.P. and G.G. drafted the paper; P.M., A.L., J.T.H., T.B. and F.G. revised the paper; all authors approved the final version of the manuscript. All the authors have accepted responsibility for the entire content of this submitted manuscript and approved submission.

  2. Research funding: None declared.

  3. Employment or leadership: None declared.

  4. Honorarium: None declared.

  5. Competing interests: The funding organization(s) played no role in the study design; in the collection, analysis, and interpretation of data; in the writing of the report; or in the decision to submit the report for publication.

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Received: 2019-06-08
Accepted: 2019-08-07
Published Online: 2019-09-02
Published in Print: 2020-01-28

© 2019 Walter de Gruyter GmbH, Berlin/Boston

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https://doi.org/10.1515/cclm-2019-0568
Keywords for this article
acid-base disorder; albumin-adjusted calcium; ionized calcium; mineral and bone metabolism disorders; Payne formula; total calcium

Articles in the same Issue

  1. Frontmatter
  2. Editorial
  3. Towards a personalized assessment of vitamin D status
  4. Reviews
  5. Circulating tumor DNA and their added value in molecular oncology
  6. Telomere length determinants in childhood
  7. Opinion Papers
  8. Serum or plasma? An old question looking for new answers
  9. Evaluating sample stability in the clinical laboratory with the help of linear and non-linear regression analysis
  10. General Clinical Chemistry and Laboratory Medicine
  11. Simultaneous measurement of 25(OH)-vitamin D and 24,25(OH)2-vitamin D to define cut-offs for CYP24A1 mutation and vitamin D deficiency in a population of 1200 young subjects
  12. How well do Croatian laboratories adhere to national recommendations for laboratory diagnostics of chronic kidney disease (CKD)?
  13. Underfilling of vacuum blood collection tubes leads to increased lactate dehydrogenase activity in serum and heparin plasma samples
  14. Calcium state estimation by total calcium: the evidence to end the never-ending story
  15. The use of faecal immunochemical testing in the decision-making process for the endoscopic investigation of iron deficiency anaemia
  16. Measurement uncertainty of β-lactam antibiotics results: estimation and clinical impact on therapeutic drug monitoring
  17. Practical approach to method verification in plasma and validation in cerebrospinal fluid under accreditation using a flexible scope in molecular virology: setting up the HIV, HBV and HCV Aptima™ Quant Dx assays
  18. Plasma neurofilament light chain is associated with mortality after spontaneous intracerebral hemorrhage
  19. Comparison of the diagnostic performance of two automated urine sediment analyzers with manual phase-contrast microscopy
  20. Development and validation of LC-MS/MS methods to measure tobramycin and lincomycin in plasma, microdialysis fluid and urine: application to a pilot pharmacokinetic research study
  21. Reference Values and Biological Variations
  22. Cord blood S100B: reference ranges and interest for early identification of newborns with brain injury
  23. Hematology and Coagulation
  24. Validation and standardization of the ETP-based activated protein C resistance test for the clinical investigation of steroid contraceptives in women: an unmet clinical and regulatory need
  25. Cancer Diagnostics
  26. Next-generation sequencing for tumor mutation quantification using liquid biopsies
  27. Cardiovascular Diseases
  28. Evolution of the slopes of ST2 and galectin-3 during marathon and ultratrail running compared to a control group
  29. Letters to the Editor
  30. Biological variation of two serum markers for preeclampsia prediction
  31. Daily monitoring of a control material with a concentration near the limit of detection improves the measurement accuracy of highly sensitive troponin assays
  32. Are patients adequately informed about procedures for 24-h urine collection?
  33. Interferences in free thyroxine concentration using the Roche analytical platform: improvement of the third generation?
  34. Procedures for the diagnosis of macro-follicle stimulating hormone (FSH) in a patient with high serum FSH concentrations
  35. False-positive result of immunochromatographic (IC) strip test for the diagnosis of α-thalassemia in samples with autoantibodies
  36. Sample dilution for soluble interleukin-2 receptor α measurement: comparison of two different matrices
  37. The growing problem of predatory publishing: a case report
  38. Cerebrospinal fluid lactate levels according to the site of puncture
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