Abstract:

Objective To analyze the levels of 25-hydroxyvitamin D [25（OH）D] in healthy subjects. Methods A multicenter retrospective study was conducted in 974 healthy subjects who were enrolled from 3 laboratories. The 25-hydroxyvitamin D₂ [25（OH）D₂] and 25-hydroxyvitamin D₃ [25（OH）D₃] levels were determined by isotope dilute liquid chromatography tandem mass spectrometry（ID LC-MS/MS）. The data were analyzed statistically. Results After removing 23 outliers,serum 25（OH）D₂,25（OH）D₃ and 25（OH）D levels of 951 healthy subjects were non-normally distributed. Female serum 25（OH）D₃ and 25（OH）D levels were higher than those in males（P<0.01）,and there was no statistical significance for serum 25（OH）D₂ levels between males and females（P>0.05）. The healthy subjects were classified into 1-17 years old group,18-29 years old group,30-39 years old group,40-49 years old group,50-59 years old group,60-69 years old group,70-79 years old group,80-89 years old group and 90-100 years old group. The 25（OH）D levels of males and females in 1-17 years old group were higher than those in the other age groups（P<0.01）. There was no statistical significance in 25（OH）D levels in 18-79 years old groups（P>0.05）. Those in 80-89 years old group and 90-100 years old group were lower than those in the other age groups（P<0.05,P<0.01）. Comparing those of males and females in the same age group,the 25（OH）D levels of females >50 years old were higher than those of males（P<0.01）,and there was no statistical significance between males and females in the other age groups（P>0.05）. The percentile method was used to evaluate serum 25（OH）D levels in healthy subjects,of which that of females was 3.5-31.5 ng/mL,and that of males was 2.7-29.8 ng/mL. Conclusions The distribution of serum 25（OH）D levels of healthy subjects based on mass spectrometry provides a reference for clinical diagnosis and treatment.

Key words: 25-Hydroxyvitamin D, Isotope dilute liquid chromatography tandem mass spectrometry, Healthy subject