24-hour urinary 6-hydroxymelatonin sulfate excretion in patients with ulcerative colitis

The cause and factors determining the chronic course of ulcerative colitis (UC) remain unknown. Melatonin is synthetised in the gastrointestinal tract and plays a crucial role in the protection of gastrointestinal mucosa and modulation of the immune system. Melatonin is metabolised to 6-hydroxymelatonin sulfate (6HMS) and excreted into urine. Urine 6HMS concentration corresponds well with the total level of melatonin in the body. The aim of the study was to evaluate 24-hour urine excretion of 6HMS in UC and its correlation with severity of the disease.

Methods: The studied group comprised 24 patients with UC (aged 17-58 years, mean age 33 years) admitted on the reason of UC relapse. The control group comprised 25 healthy volunteers (aged 18-49 years, mean age 35 years). The patients with UC were clinically scored and underwent colonoscopy. The subjects collected the total volume of urine excreted during a 24-hour period. 6HMS in urine was calculated using ELISA method. RESULTS. The average 24-hour urine excretion of 6HMS was 26.06 +/- 15.15 microg in UC patients and 15.09 +/- 6.37 microg in healthy subjects (p < 0.001). The urine level of 6HMS tended to be increased in mild related to severe course of the disease.

Conclusions: The average 24-hour urine excretion of 6HMS in UC patients is higher than in healthy persons and negatively associated with severity of UC. Melatonin seems to be a part of anti-inflammatory response and its high level may appease the course of UC.