The cut-off values of vitamin D deficiency in early infancy

Kazushige Ikeda, Kaori Hara-Isono, Keigo Takahashi, Takeshi Arimitsu, Yasunori Sato

Research output: Contribution to journalArticlepeer-review


Background: Several cut-off points for 25-hydroxyvitamin D (25(OH)D) levels have been proposed to determine vitamin D deficiency or insufficiency. However, the level for 25(OH)D deficiency in early infancy remains unclear. The serum 25(OH)D value at which parathyroid hormone level plateaus, called the “inflection point,” is considered the most appropriate criterion for defining an adequate vitamin D status. Methods: This was a single-center retrospective study involving 305 1-month-old and 252 2-month-old Japanese infants. Nonlinear segmented regression analysis was performed based on the correlation between 25(OH)D and parathyroid hormone levels to determine vitamin D deficiency cut-off points. Results: Inflection points were 7.90 ng/mL for 1-month-old (95% confidence interval, 6.31–9.49) and 6.74 ng/mL for 2-month-old (95% confidence interval, 5.80–7.68) Japanese infants, which were lower than previously reported. Cut-off values were also lower in the high-body mass index (BMI) group than in the low-BMI group for both 1-month and 2-month-old infants. Conclusion: These results imply the need for nutritional rickets prevention via policy recommendations in most full-term newborns in Japan. Although validation studies are required, these results can still be used to guide vitamin D insufficiency treatment options in early infancy.

Original languageEnglish
Pages (from-to)361-367
Number of pages7
JournalPediatrics and Neonatology
Issue number4
Publication statusPublished - 2022 Jul


  • 25-hydroxyvitaminD
  • broken line regression
  • cut-off value
  • inflection point
  • vitamin D deficiency

ASJC Scopus subject areas

  • Pediatrics, Perinatology, and Child Health


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