690 - Gestational age-specific percentile-based reference values of serum alkaline phosphatase in Japanese neonates

Poster Number: 690
Publication Number: 690.232

Koichiro Hara, Nihon University, Itabashi, Tokyo, Japan; Nobuhiko Nagano, Department Pediatrics and Child Health, Nihon Uviversity School of Medicine, Itabashi-ku, Tokyo, Japan; Daichi Katayama, Nihon University Itabashi Hospital, meguro, Tokyo, Japan; Takuya Akimoto, Nihon University school of medicine, Itabashi, Tokyo, Japan; Takayuki Imaizumi, Nihon University, Itabashi-ku, Tokyo, Japan; Ayako Seimiya, Department of Pediatrics and Child Health, Nihon University School of Medicine, Tokyo, Tokyo, Japan; Ryoji Aoki, Nihon University School of Medicine, Itabashi-ku, Tokyo, Japan; Midori Hijikata, Nihon University Itabashi Hospital, itabashi, Tokyo, Japan; Aya Okahashi, Nihon university school of medcine, Itabashi, Tokyo, Japan; Ichiro Morioka, Nihon University School of Medicine, Itabashi, Tokyo, Japan

Background: Serum alkaline phosphatase (ALP) levels are an important index for evaluating osteogenesis in neonates – being low in neonates with hypophosphatasia. However, percentile-based ALP reference values at birth have not been established in Japanese neonates as yet.

Objective:

To create percentile-based ALP reference values at birth in Japanese neonates and characterize their dependence on sex, gestational age (GA), and anthropometric values.

Design/Methods: A hospital-based prospective study was conducted at Nihon University Itabashi Hospital with approval by the Ethic Committees (no. RK-220913-2). Japanese neonates who underwent a blood test within 24 hours after birth between 2020 and 2022 were enrolled. To create percentile-based ALP reference values, we classified the neonates into four GA groups: extremely preterm, < 28 wks; early preterm, 28–33 wks; late preterm, 34–36 wks; and term, ≥37 wks. The 10, 25, 50, 75, and 90% percentile values of ALP levels at birth were then calculated using the International Federation of Clinical Chemistry method. ALP levels at birth were compared among the four groups. Univariate and multivariate analyses revealed the relationship between ALP levels at birth, sex, GA, birth weight (BW), height, and head circumference.

Results: 440 neonates were enrolled (27 extremely preterm; 69 early preterm; 160 late preterm; and 184 term). Percentile-based ALP reference values at birth are shown in Table 1. ALP levels at birth were significantly higher with shorter GA. There was no sex difference in ALP levels at birth (p = 0.383). A negative correlation was observed with GA, BW, height, and head circumference by univariate analyses (p< 0.01). In a multivariate analysis, only GA was independently associated with ALP levels at birth (logarithmic worth 4.18, p< 0.001, Table 2).

Conclusion(s): Percentile-based ALP reference values at birth in Japanese neonates are dependent primarily on GA.