title: Low Testosterone Levels and Reduced Kidney Function in Japanese Adult Men: The Locomotive Syndrome and Health Outcome in Aizu Cohort Study.
abstract: OBJECTIVE
  Findings from several experimental studies in animals have suggested a protective action of testosterone on kidney function, but hard evidence for such an association in humans is scarce. We examined the association between testosterone levels and kidney function among adult men living in super-aged communities.
  
  
  METHODS
  We conducted cross-sectional study involving residents aged 40-80 years who participated in annual health check-ups in 2 communities. A total of 1031 men were recruited in 2010. Main exposure was salivary testosterone (sT) levels measured using an enzyme-linked immunosorbent assay. Main outcome was estimated glomerular filtration rate (eGFR) determined by age, gender, and serum creatinine levels.
  
  
  RESULTS
  For the 848 participants analyzed, median age and eGFR were 69 years and 69.1 mL/min/1.73 m(2), respectively. On comparison of 90th-percentile sT levels with lower levels, our general linear model with restricted cubic splines showed that lower sT levels were associated with decreased eGFR after adjustment for sociodemographic characteristics, comorbidities, and blood pressure. For example, fifth percentile sT was associated with decreased eGFR, with a difference in eGFR [-3.43 mL/min/1.73 m(2) (95% confidence interval, CI -6.02 to -0.84)] comparable in magnitude to the reduction in eGFR observed for a 6-year increase in age in our population. The association between low testosterone levels and decreased eGFR remained similar even when analyses were restricted to participants aged over 60 years (734 participants, median age 71 years).
  
  
  CONCLUSIONS
  Results from our study indicated that having low testosterone levels was independently associated with reduced eGFR in adult men. Our finding of this association between low testosterone levels and reduced kidney function needs to be corroborated among persons with chronic kidney disease or in a longitudinal study.
authors.affiliation: Department of Innovative Research and Education for Clinicians and Trainees (DiRECT), Fukushima Medical University Hospital, Fukushima, Japan; Department of Healthcare Epidemiology, School of Public Health in the Graduate School of Medicine, Kyoto University, Kyoto, Japan.
authors.forename: Noriaki
authors.initials: N
authors.lastname: Kurita
authors.affiliation: Department of Urology, Juntendo University School of Medicine, Tokyo, Japan.
authors.forename: Shigeo
authors.initials: S
authors.lastname: Horie
authors.affiliation: Department of Healthcare Epidemiology, School of Public Health in the Graduate School of Medicine, Kyoto University, Kyoto, Japan.
authors.forename: Shin
authors.initials: S
authors.lastname: Yamazaki
authors.affiliation: Department of Orthopedic Surgery, Fukushima Medical University School of Medicine, Fukushima, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Otani
authors.affiliation: Department of Orthopedic Surgery, Fukushima Medical University School of Medicine, Fukushima, Japan.
authors.forename: Miho
authors.initials: M
authors.lastname: Sekiguchi
authors.affiliation: Institute for Health Outcomes and Process Evaluation Research (i-Hope International), Kyoto, Japan.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Onishi
authors.affiliation: Department of Preventive Medicine and Epidemiologic Informatics, National Cerebral and Cardiovascular Center, Osaka, Japan.
authors.forename: Misa
authors.initials: M
authors.lastname: Takegami
authors.affiliation: Department of Community Health Sciences, Kobe University Graduate School of Health Sciences, Kobe, Japan.
authors.forename: Rei
authors.initials: R
authors.lastname: Ono
authors.affiliation: Department of Orthopedic Surgery, Fukushima Medical University School of Medicine, Fukushima, Japan.
authors.forename: Shin-ichi
authors.initials: S
authors.lastname: Konno
authors.affiliation: Department of Orthopedic Surgery, Fukushima Medical University School of Medicine, Fukushima, Japan.
authors.forename: Shin-ichi
authors.initials: S
authors.lastname: Kikuchi
authors.affiliation: Department of Healthcare Epidemiology, School of Public Health in the Graduate School of Medicine, Kyoto University, Kyoto, Japan; Center for Innovative Research for Communities and Clinical Excellence (CIRC(2)LE), Fukushima Medical University, Fukushima, Japan. Electronic address: fukuhara.shunichi.6m@kyoto-u.ac.jp.
authors.forename: Shunichi
authors.initials: S
authors.lastname: Fukuhara
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D003404:Creatinine / Q000097:blood; D003430:Cross-Sectional Studies; D004797:Enzyme-Linked Immunosorbent Assay; D005919:Glomerular Filtration Rate; D006801:Humans; D007564:Japan; D008297:Male; D008875:Middle Aged; D013739:Testosterone / Q000032:analysis*
chemical_list: D013739:Testosterone; D003404:Creatinine
keywords: Testosterone; aging; estimated glomerular filtration rate