Determination of optimal blood calcium thresholds in children with hereditary forms of hypoparathyroidism during therapy

Dzhamaludinova A.A., Sozaeva L.S., Chugunov I.S., Peterkova V.A., Mokrysheva N.G.

Endocrinology Research Centre, Russia

Background: Hypoparathyroidism (HypoPT) is characterized by persistent hypocalcemia, requiring lifelong therapy with active forms of vitamin D in combination with calcium (Ca) supplements. Maintaining serum Ca levels at the lower limit of normal is recommended to prevent hypercalciuria; however, safe thresholds have not been determined. In addition to hypocalcemia, HypoPT is associated with hyperphosphatemia, which is an additional risk factor for complications.
Objective: Determination of threshold blood Ca levels associated with an increased risk of hypercalciuria in children with HypoPT treated with active forms of vitamin D and assessment of the incidence of hyperphosphatemia in patients with values above and below the identified thresholds.
Materials and methods: This retrospective study with a prospective component assessed clinical and laboratory data from 262 inpatient episodes in 63 patients with congenital forms of HypoPT at the Endocrinology Research Centre (patients were examined at the center multiple times). Descriptive and comparative statistics were used, as well as ROC analysis with cut-off points determined using the Youden test.
Results: The first stage involved comparing inpatient episodes with and without hypercalciuria. Statistically significant differences in the levels of total, albumin-corrected, and ionized serum Ca in the analysis of a single urine sample (p<0.001), as well as in the level of total serum Ca in the assessment of 24-hour urinary calcium excretion (p<0.006) were found. Based on the ROC analysis, the following threshold values of calcemia associated with the risk of hypercalciuria in a single urine portion were determined: for total blood Ca – 2.21 mmol/L, for albumin-corrected – 2.15 mmol/L, for ionized Ca – 1.03 mmol/L. At the second stage, the frequency of hyperphosphatemia depending on the achievement of these threshold values was assessed. No statistically significant differences in the frequency of hyperphosphatemia between visits with Ca levels above and below the threshold values were found (p=0.017 after Bonferroni correction, two-tailed Fisher’s exact test). At the same time, a trend toward a higher incidence of hyperphosphatemia at Ca concentrations below established thresholds was noted. 
Conclusion: The study identified blood Ca levels associated with a high risk of hypercalciuria in children with HypoPT. Hyperphosphatemia persisted both when Ca levels were maintained below and above established thresholds. The study results highlight the need to optimize therapeutic approaches for HypoPT in children.

For citations: Dzhamaludinova A.A., Sozaeva L.S., Chugunov I.S., Peterkova V.A., Mokrysheva N.G. Determina-tion of optimal blood calcium thresholds in children with hereditary forms of hypoparathyroidism during therapy. Pharmateca. 2026;33(2):82-89. (In Russ.). DOI: https://dx.doi.org/10.18565/pharmateca.2026.2.82-89

Authors’ contribution: A.A. Dzhamaludinova, L.S. Sozaeva – research and analysis, preparation the final version of the article. I.S. Chugunov, V.A. Peterkova, N.G. Mokrysheva – editing the text, provision of valuable comments. All authors approved the final version of the article before publication and agreed to be accountable for all aspects of the work, including appropriately reviewing and resolving questions related to the accuracy or integrity of any part of the work.
Conflicts of interest: The authors confirm that they have no conflicts of interest to declare.
Funding: This work was carried out at the authors’ own initiative without the receipt of additional funding.
Ethical Approval: The study was approved by the Local Ethics Committee of the Endocrinology Research Centre (Protocol No. 16 dated September 13, 2023).
Patient Consent for Publication: The retrospective design of the study did not require informed consent from patients for statistical processing of anonymized data for subsequent publication.
Authors’ Data Sharing Statement: The data supporting the findings of this study are available upon request from the corresponding author after approval from the principal investigator.

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About the Authors

A.A. Dzhamaludinova, Clinical Postgraduate Student, Endocrinology Research Centre, Moscow, Russia; A.Dzhamaludinova@mail.ru, ORCID: https://orcid.org/0009-0006-9482-5901, eLibrary SPIN: 1260-2455 (corresponding author)
L.S. Sozaeva, Cand. Sci. (Med.), Endocrinology Research Centre, Moscow, Russia; Leila.sozaeva@gmail.com, ORCID: http://orcid.org/0000-0002-5650-1440, eLibrary SPIN: 9983-5662
I.S. Chugunov, Cand. Sci. (Med.), Endocrinology Research Centre, Moscow, Russia; chugunovigor@gmail.com, ORCID: https://orcid.org/0000-0003-4915-1267, SPIN code: 1514-5005
V.A. Peterkova, Dr. Sci. (Med.), Professor, Academician of the Russian Academy of Sciences, Endocrinology Research Centre, Moscow, Russia; peterkovava@hotmail.com, ORCID: https://orcid.org/0000-0002-5507-4627, SPIN: 4009-2463
N.G. Mokrysheva, Dr. Sci. (Med.), Professor, Academician of the Russian Academy of Sciences, Endocrinology Research Centre, Moscow, Russia; mokrisheva.natalia@endocrincentr.ru, ORCID: https://orcid.org/0000-0002-9717-9742, eLibrary SPIN: 5624-3875

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