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Determination of a Serum 25-Hydroxyvitamin D Reference Ranges in Japanese Adults Using Fully Automated Liquid
Hiroyasu Miyamoto1, Daisuke Kawakami2, Nobuhiro Hanafusa3
1Department of Laboratory Medicine, The Jikei University School of Medicine, Minato City, Tokyo, Japan; Department of Central Clinical Laboratory, The Jikei University Hospital, Minato City, Tokyo, Japan; Department of International Food and Agricultural Science, Faculty of International Agriculture and Food Studies, Tokyo University of Agriculture, Setagaya City, Tokyo, Japan.
Most urban Japanese adults have insufficient vitamin D levels, with 98% showing inadequate 25-hydroxyvitamin D (25(OH)D) concentrations. This study establishes new reference ranges for 25(OH)D in a Japanese urban population.
Area of Science:
- Clinical biochemistry
- Nutritional science
- Public health
Background:
- Establishing vitamin D reference ranges is challenging due to measurement standardization issues and lifestyle influences.
- Vitamin D status is of increasing interest globally, yet definitive reference ranges remain elusive.
Purpose of the Study:
- To determine the current reference concentration of 25-hydroxyvitamin D (25(OH)D) in a healthy urban Japanese population.
- To establish population-specific reference ranges for vitamin D status.
Main Methods:
- Utilized a fully automated liquid chromatography-tandem mass spectrometry (LC-MS/MS) system for precise 25(OH)D measurement.
- Validated accuracy against commercial immunoassays and assessed reproducibility.
- Conducted mass screening of 5518 participants in Tokyo for serum 25(OH)D concentrations.
Main Results:
- The automated LC-MS/MS system demonstrated good reproducibility and accuracy.
- A high prevalence of vitamin D inadequacy was observed, with 98% of participants below 30 ng/mL.
- Established reference ranges for total 25(OH)D: 7-30 ng/mL (female), 5-27 ng/mL (male), and 6-29 ng/mL (total).
Conclusions:
- Urban Japanese lifestyle factors, such as reduced outdoor time and dietary changes, likely contribute to widespread vitamin D insufficiency.
- The validated LC-MS/MS system is crucial for future longitudinal studies and mass screenings to understand vitamin D status discrepancies.
- Further research is needed to reconcile observed vitamin D levels with official guidelines.
