Melatonin intake before intradialytic exercise reverses oxidative stress and improves antioxidant status in hemodialysis patients.

Purpose: The present study aimed to investigate for the first time the effects of melatonin (MEL) intake on oxidative stress and cellular damage during intradialytic exercise (IEX).

Methods: Thirteen hemodialysis (HD) patients volunteered to participate in the current randomized crossover trial. Participants performed four HD sessions in four different conditions: (Exercise (EX)-MEL), (EX-Placebo (PLA)), (Control (C)-MEL), and (C-PLA). 3 mg of MEL or PLA were taken 60 min before starting exercise, or at the equivalent time in the C conditions. Blood samples were taken before HD (T0), immediately after the end of IEX (T1), 60 min after IEX (T2), or at the corresponding times in the C conditions to measure free radicals damage, antioxidant biomarkers, as well as biomarkers of muscle and liver damage.

Results: Malondialdehyde and Advanced Oxidation Protein Products decreased in (C-MEL) ( < 0.05,  = 2.19;  < 0.01,  = 0.99, respectively) at T2 compared to T0. Catalase and total thiol levels increased in (C-MEL) ( < 0.01,  = 1.51;  < 0.01,  = 1.56, respectively) and in (EX-MEL) ( = 0.01,  = 1.28;  < 0.01,  = 1.52, respectively) at T1 compared to T0. Total bilirubin levels increased in (EX-MEL) and (C-MEL) at T2 compared to T0 ( < 0.001,  = 2.77;  < 0.001,  = 1.36, respectively), but only at T2 compared to T1 in (EX-MEL) ( < 0.001,  = 1.67). In all conditions, uric acid levels decreased at T1 compared to T0 and at T2 compared to T1, while biomarkers of muscle and liver damage remained unchanged.

Conclusion: This pilot study is the first to show that MEL ingestion, alone or combined with IEX, could improve oxidant-antioxidant balance during HD.