{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,2]],"date-time":"2026-10-02T07:54:29Z","timestamp":1790927669237,"version":"4.1.0"},"reference-count":36,"publisher":"S. Karger AG","license":[{"start":{"date-parts":[[2026,8,31]],"date-time":"2026-08-31T00:00:00Z","timestamp":1788134400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/karger.com\/pages\/terms-and-conditions"},{"start":{"date-parts":[[2026,8,31]],"date-time":"2026-08-31T00:00:00Z","timestamp":1788134400000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/karger.com\/pages\/terms-and-conditions"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Horm Res Paediatr"],"abstract":"Introduction: Vitamin D metabolism is essential for calcium and phosphate homeostasis, yet reference values for its key metabolites in early childhood are lacking. This study aimed to establish percentile-based intervals for 1,25-dihydroxyvitamin D [1,25(OH)<sub>2<\/sub>D], 24,25-dihydroxyvitamin D [24,25(OH)<sub>2<\/sub>D], and the vitamin D metabolite ratio (VMR = 24,25(OH)<sub>2<\/sub>D\/25(OH)D x 100%) in healthy, well vitamin D-supplemented children under 2 years of age, providing a benchmark for disorders such as idiopathic infantile hypercalcemia. Methods: This cross-sectional study analyzed blood samples from 208 healthy full-term children undergoing elective minor surgery or diagnostic procedures at four Belgian hospitals. 25(OH)D and 24,25(OH)<sub>2<\/sub>D were measured by LC-MS\/MS and 1,25(OH)<sub>2<\/sub>D by IDS-iSYS immunoassay. The VMR (24,25(OH)<sub>2<\/sub>D<sub>3<\/sub>\/25(OH)D<sub>3<\/sub> \u00d7 100%) was calculated. The intervals were expressed as percentiles and 95% confidence intervals. Associations between clinical factors and vitamin D markers were assessed using univariate and multivariate regression analyses. Results: Population-specific percentile-based intervals applicable to vitamin D-supplemented infants (2.5th\u201397.5th percentiles) were 35.57\u2013148.55 pg\/mL for 1,25(OH)<sub>2<\/sub>D, 0.50\u20136.61 ng\/mL for 24,25(OH)<sub>2<\/sub>D and 1.95\u201315.74% for 24,25(OH)<sub>2<\/sub>D<sub>3<\/sub>\/25(OH)D<sub>3<\/sub> \u00d7 100%. Older age was associated with lower 1,25(OH)<sub>2<\/sub>D levels. The concentration of 25(OH)D was higher in older children, boys, non-Caucasians, and those with higher vitamin D supplement intake. The concentration of 24,25(OH)<sub>2<\/sub>D was positively associated with supplementation. After adjustment for relevant covariates, multivariable analysis demonstrated independent associations between VMR, ethnicity, and vitamin D supplementation, whereby Caucasian ethnicity and vitamin D supplementation were associated with higher VMR values. Discussion: These data provide the first pediatric percentile-based intervals for vitamin D metabolites in well vitamin D-supplemented children under 2 years of age, demonstrating the influence of age, body composition, supplementation, and ethnicity. These ranges can support the early diagnosis of metabolic bone disorders and guide clinical decision-making.<\/jats:p>","DOI":"10.1159\/hrp\/adaag017","type":"journal-article","created":{"date-parts":[[2026,8,22]],"date-time":"2026-08-22T11:41:23Z","timestamp":1787398883000},"page":"1-1","source":"Crossref","is-referenced-by-count":0,"title":["Distribution of Vitamin D Metabolites in Early Childhood: Findings from a Multicenter Belgian Cross-Sectional Study"],"prefix":"10.1159","author":[{"given":"Ellen","family":"Devos","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Tom","family":"Fiers","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kathleen","family":"De 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