ORIGINAL RESEARCH article
Front. Nutr.
Sec. Nutritional Epidemiology
This article is part of the Research TopicNutrition-Related Clinical Laboratory Indicators: Enhancing Precision Medicine in Disease ManagementView all 4 articles
Age-and Sex-specific Reference Intervals and Determinants of Plasma Vitamin B6 Metabolites in Healthy Chinese Adults
Provisionally accepted
Yazhao Mei
Ziyuan Wang
Li Shen
Zhen-lin Zhang
Hua Yue
Hao Zhang
Jie Mei Gu
Weiwei Hu
Shan-Shan LiChao Gao
Zhe Wei
Yang XuJie WangGao Gao
Chun Wang*- Shanghai 6th Peoples Hospital Affiliated to Shanghai Jiao Tong University, Shanghai, China
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Objective: Reference intervals (RIs) for vitamin B6 biomarkers remain underexplored in Chinese adults. We aimed to establish age-and sex-specific RIs of pyridoxal 5′-phosphate (PLP), pyridoxal (PL), 4-pyridoxic acid (PA), and their ratios (PLP/PL, PLP/PA, and PAr), and to identify independent determinants of these markers. Methods: Vitamin B6 metabolites were measured by liquid chromatography–tandem mass spectrometry (LC-MS/MS). The distribution changes were illustrated by sex-stratified age percentile curves (P10/P50/P90). Robust 95% RIs (P2.5–P97.5) were obtained by sex and age (<50 vs ≥50 years) using the Horn–Pesce method. Sex-stratified multivariable linear regression was conducted to identify the independent determinants of vitamin B6 biomarkers. Results: This study included a community-based sample of 367 healthy adults (197 males and 170 females) with a median age of 49.0 years (range 20.0-80.0 years). Females had higher PLP, PL and PLP/PA, and lower PAr than males (all P<0.01). In males, percentile curves and age-group contrasts showed age-associated declines in PLP, PLP/PL and PLP/PA and an increase in PAr (all P<0.05); corresponding indices in females were largely stable. The RIs of PLP (nmol/L) were 10.36–145.87 (males <50 years, n=103), 13.03–103.46 (females <50 years, n=87), 9.27–142.96 (males ≥50 years, n=94), and 16.83–173.06 (females ≥50 years, n=83), respectively. Higher ALP levels were associated with lower PLP, PLP/PL and PLP/PA, and higher PAr; albumin was positively related to PLP/PL and PLP/PA, and negatively to PAr; eGFR was positively correlated with PLP/PA, and negatively with PAr. Conclusion: We established population-specific, age-and sex-stratified RIs for vitamin B6 biomarkers in healthy Chinese adults, providing a baseline for clinical and laboratory assessment of vitamin B6 metabolism. We also found that ALP, albumin, renal function, and serum phosphorus were closely related to the vitamin B6 status in both males and females.
Keywords: 4-Pyridoxic acid, Multivariate linear regression, Pyridoxal, Pyridoxal 5′-phosphate, Reference interval
Received: 06 Jan 2026; Accepted: 27 Jan 2026.
Copyright: © 2026 Mei, Wang, Shen, Zhang, Yue, Zhang, Gu, Hu, Li, Gao, Wei, Xu, Wang, Gao and Wang. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Chun Wang
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