Alkaline phosphatase in pediatric patients with genu varum caused by vitamin D-deficient rickets

Masashi Mukai; Takehisa Yamamoto; Shinji Takeyari; Yasuhisa Ohata; Taichi Kitaoka; Takuo Kubota; Katsusuke Yamamoto; Eri Kijima; Yasuhiro Hasegawa; Toshimi Michigami; Keiichi Ozono

doi:10.1507/endocrj.EJ20-0622

ORIGINAL

Alkaline phosphatase in pediatric patients with genu varum caused by vitamin D-deficient rickets

Masashi Mukai, Takehisa Yamamoto, Shinji Takeyari, Yasuhisa Ohata, Taichi Kitaoka, Takuo Kubota, Katsusuke Yamamoto, Eri Kijima, Yasuhiro Hasegawa, Toshimi Michigami, Keiichi Ozono

Author information

Masashi Mukai
Department of Pediatrics, Minoh City Hospital, Osaka, Japan
Takehisa Yamamoto
Department of Pediatrics, Minoh City Hospital, Osaka, Japan
Shinji Takeyari
Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan
Yasuhisa Ohata
Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan
Taichi Kitaoka
Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan
Takuo Kubota
Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan
Katsusuke Yamamoto
Department of Pediatric Nephrology and Metabolism, Osaka Women’s and Children’s Hospital, Osaka, Japan
Eri Kijima
Department of Pediatrics, Minoh City Hospital, Osaka, Japan
Yasuhiro Hasegawa
Department of Pediatrics, Minoh City Hospital, Osaka, Japan
Toshimi Michigami
Department of Bone and Mineral Research, Osaka Women’s and Children’s Hospital, Osaka, Japan
Keiichi Ozono
Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan

Keywords: Genu varum, Alkaline phosphatase, Linear mixed model analysis, Structural equation modeling analysis, Neural network analysis

JOURNAL FREE ACCESS FULL-TEXT HTML

2021 Volume 68 Issue 7 Pages 807-815

DOI https://doi.org/10.1507/endocrj.EJ20-0622

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Abstract

An elevated serum alkaline phosphatase (ALP) level is one of the markers for the presence of rickets in children, but it is also associated with bone formation. However, its role in diagnosing genu varum in pediatric patients with vitamin D-deficient rickets is still unknown. To clarify the role of the serum ALP level in assessing the severity of genu varum, we retrospectively investigated this issue statistically using data on rickets such as serum intact parathyroid hormone (iPTH), 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, ALP, the level of creatinine as the percentage of the median according to age (%Cr), and the metaphyseal diaphyseal angle (MDA) in the lower extremities as an index of the severity of genu varum. A multiple regression analysis revealed that log ALP and %Cr values were negatively associated with MDA values. The former association was also confirmed by a linear mixed model, while iPTH was positively associated with MDA by path model analysis. To elucidate the association of ALP with MDA in the presence of iPTH, we investigated three-dimensional figures by neural network analysis. This indicated the presence of a biphasic association of ALP with MDA: the first phase increases while the second decreases MDA. The latter phenomenon is considered to be associated with the increase in bone formation due to the mechanical stress loaded on the lower extremities. These findings are important and informative for pediatricians to understand the significance of the serum ALP level in pediatric patients with genu varum caused by vitamin D deficiency.

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