Urinary 6-sulphatoxymelatonin levels in patients with senile cataracts

BACKGROUND: The antioxidant melatonin effectively scavenges highly toxic hydroxyl radicals. Decreases in circulating melatonin levels have been reported in patients with diseases that become more serious with advancing age. The purpose of the present study was to explore the relationship between circulatory melatonin level and the extent of senile cataracts. To this end, we assessed the urinary excretion levels of 6-sulphatoxymelatonin (aMTS6), a major metabolite of melatonin. METHODS: A total of 22 patients (aged 64 ± 7 years; 12 males and 10 females) with senile cataracts and 22 healthy controls (aged 61 ± 8 years, 12 males and 10 females) were studied. aMTS6 urine levels were measured using commercial ELISA kits. Each aMTS6 level was expressed as [aMTS6] (in ng)/[mg] creatinine. As the data were not normally distributed, the Mann–Whitney U-test was employed to assess the statistical validity of the difference observed. RESULTS: The aMT6 level in nocturnal urine was 17.87 ± 14.43 ng aMTS6/mg creatinine (mean ± SD) in senile cataract patients; this was 76% of the level measured in age- and gender-matched controls (23.28 ± 16.27 ng aMTS6/mg creatinine). This difference in nocturnal urine aMTS6 level between senile cataract patients and controls was not statistically significant (p = 0.358). CONCLUSION: The urinary aMTS6 level did not differ between subjects with and without senile cataracts.