title: Urinary 6-sulfatoxymelatonin level in age-related macular degeneration patients.
abstract: OBJECTIVE
  Melatonin is a potent antioxidant and free radical scavenger. It has been reported that serum melatonin level is relevant to certain aging diseases. The purpose of this study was to investigate melatonin levels in age-related macular degeneration (AMD) patients by measurement of 6-sulfatoxymelatonin levels (aMT6s), the major metabolite of melatonin in urine, and compare it with a group of age- and gender-matched controls.
  
  
  METHODS
  The first urine of the morning was collected from 43 AMD patients and 12 controls who did not have AMD. The level of aMT6s in specimens was measured by a commercial 6-sulfatoxymelatonin ELISA kit. The assay was performed by researchers, who were masked to the clinical information. To adjust for variation in the diluteness of urine, urinary creatinine level was measured and aMT6s levels were expressed as aMT6s/creatinine.
  
  
  RESULTS
  The level of urinary aMT6s/creatinine (mean+/-SD) in AMD (6.24+/-3.45 ng aMT6s/mg creatinine) was significantly lower than that of the controls (10.40+/-4.51, p=0.0128). After adjustment for various factors (age, smoking, cancer, and coronary heart disease) that may influence the aMT6s level, the odds-ratio of urinary aMT6s comparing AMD patients to controls was 0.65 (95% confidence interval=0.48-0.88, p=0.0036), indicating that urinary aMT6s level in AMD patients was lower than in controls even after multivariate adjustment.
  
  
  CONCLUSIONS
  Urinary aMT6s level in AMD patients was 40% lower than in age- and gender-matched controls. This difference between AMD patients and controls is present after adjustment for the factors of age, smoking, and histories of cancer and coronary heart disease. The significance of this result and the role of melatonin in the occurrence of AMD require further investigation.
authors.affiliation: Department of Ophthalmology, New York Eye and Ear Infirmary, New York, NY 10003, USA.
authors.forename: Richard
authors.initials: R
authors.lastname: Rosen
authors.forename: Dan-Ning
authors.initials: DN
authors.lastname: Hu
authors.forename: Violete
authors.initials: V
authors.lastname: Perez
authors.forename: Katy
authors.initials: K
authors.lastname: Tai
authors.forename: Guo-Pei
authors.initials: GP
authors.lastname: Yu
authors.forename: Min
authors.initials: M
authors.lastname: Chen
authors.forename: Paul
authors.initials: P
authors.lastname: Tone
authors.forename: Steven A
authors.initials: SA
authors.lastname: McCormick
authors.forename: Joseph
authors.initials: J
authors.lastname: Walsh
mesh_terms: D000368:Aged; D000375:Aging / Q000652:urine*; D016022:Case-Control Studies; D003404:Creatinine / Q000652:urine; D003710:Demography; D005260:Female; D006801:Humans; D008268:Macular Degeneration / Q000652:urine*; D008297:Male; D008550:Melatonin / Q000031:analogs & derivatives* / Q000652:urine
chemical_list: C054513:6-sulfatoxymelatonin; D003404:Creatinine; D008550:Melatonin