title: Urine melatonin levels are inversely associated with sarcopenia in postmenopausal women.
abstract: OBJECTIVE
  Mainly secreted in the pineal gland, melatonin is a neurohormone that has versatile functions, including cellular protection. Decreased melatonin levels are associated with the aging process and age-related conditions. Melatonin may be associated with sarcopenia because it is one of the most common age-related diseases and because disrupted cellular vitality in skeletal muscle is known to be involved in its pathogenesis. Therefore, we investigated the relationship between first-morning-urine 6-sulfatoxymelatonin (aMT6s) levels and sarcopenia in Korean postmenopausal women.
  
  
  METHODS
  Seventy-eight Korean postmenopausal women participated. Biomarkers of metabolic risk factors, along with the presence of sarcopenia, were assessed using dual-energy x-ray absorptiometry. Urine aMT6s levels were measured using enzyme-linked immunosorbent assay.
  
  
  RESULTS
  The prevalence of sarcopenia increased significantly with increasing aMT6s quartiles. Furthermore, multivariate logistic regression analysis showed that the fourth aMT6s quartile was associated with sarcopenia, with an adjusted odds ratio of 0.13 (95% CI, 0.03-0.70; P = 0.02).
  
  
  CONCLUSIONS
  Our study shows an inverse association between urine melatonin and sarcopenia, suggesting that melatonin may have a protective role in the pathophysiology of sarcopenia. Further studies are required to better understand the clinical significance of our findings.
authors.affiliation: From the 1Department of Family Medicine, Severance Hospital, College of Medicine, Yonsei University, Seodaemun-gu, Korea; and 2Department of Family Medicine, Chung-Ang University Medical Center, Dongjak-gu, Seoul, Korea.
authors.forename: Jee-Yon
authors.initials: JY
authors.lastname: Lee
authors.forename: Jung-Ha
authors.initials: JH
authors.lastname: Kim
authors.forename: Duk-Chul
authors.initials: DC
authors.lastname: Lee
mesh_terms: D015502:Absorptiometry, Photon; D015415:Biomarkers / Q000652:urine; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008550:Melatonin / Q000031:analogs & derivatives* / Q000502:physiology / Q000652:urine*; D008875:Middle Aged; D017698:Postmenopause / Q000652:urine*; D056910:Republic of Korea; D055948:Sarcopenia / Q000000981:diagnostic imaging / Q000652:urine*
chemical_list: D015415:Biomarkers; C054513:6-sulfatoxymelatonin; D008550:Melatonin