title: Serum 25-hydroxyvitamin D levels and testosterone deficiency in middle-aged Korean men: a cross-sectional study.
abstract: Previous studies have demonstrated that male hypogonadism is associated with a low level of vitamin D. However, no reports have investigated the effects of vitamin D on testosterone levels in Korean men. Our aim was to investigate whether testosterone levels are associated with serum vitamin D levels and whether seasonal variation exists. This cross-sectional study analyzed serum 25-hydroxyvitamin D [25(OH)D], total testosterone (TT), and free testosterone (FT) in 652 Korean men over 40 years of age who had undergone a comprehensive medical examination. The average age of the subjects was 56.7 ± 7.9 years, and the mean serum 25(OH)D, TT and FT levels were 21.23 ± 7.9 ng ml-1 , 4.70 ± 1.6 ng ml-1 , and 8.12 ± 3.3 pg ml-1 , respectively. In the multiple linear regression model, 25(OH)D showed positive association with TT (β =0.137, P< 0.001) and FT (β =0.103, P= 0.008). 25(OH)D and FT showed similar seasonal or monthly variation after adjustment for age. A vitamin D deficiency [25(OH)D < 20 ng ml-1 ] was associated with an increased risk of deficiencies of TT (<2.30 ng ml-1 ) (odds ratio [OR]: 2.65; 95% confidence interval [CI]: 1.21-5.78, P= 0.014) and FT (<6.50 pg ml-1 ) (OR: 1.44; 95% CI: 1.01-2.06 P= 0.048) after adjusting for age, season, body mass index, body composition, chronic disease, smoking, and alcohol use. In conclusion, we demonstrated a positive correlation between 25(OH)D and testosterone, which showed similar seasonal variation in Korean men.
authors.forename: Young Jin
authors.initials: YJ
authors.lastname: Tak
authors.affiliation: Department of Family Medicine, Pusan National University School of Medicine; Biomedical Research Institute, Pusan National University Hospital, Busan, Korea.
authors.forename: Jeong Gyu
authors.initials: JG
authors.lastname: Lee
authors.forename: Yun Jin
authors.initials: YJ
authors.lastname: Kim
authors.forename: Nam Cheol
authors.initials: NC
authors.lastname: Park
authors.forename: Sang Soo
authors.initials: SS
authors.lastname: Kim
authors.forename: Sangyeoup
authors.initials: S
authors.lastname: Lee
authors.forename: Byung Mann
authors.initials: BM
authors.lastname: Cho
authors.forename: Eun Hee
authors.initials: EH
authors.lastname: Kong
authors.forename: Dong Wook
authors.initials: DW
authors.lastname: Jung
authors.forename: Yu Hyeon
authors.initials: YH
authors.lastname: Yi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D003430:Cross-Sectional Studies; D005058:Eunuchism / Q000097:blood* / Q000175:diagnosis* / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D056910:Republic of Korea / Q000453:epidemiology; D012621:Seasons; D013472:Sunlight; D013739:Testosterone / Q000097:blood / Q000172:deficiency*; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood
chemical_list: D015415:Biomarkers; D014807:Vitamin D; D013739:Testosterone; C104450:25-hydroxyvitamin D