Low urinary 6-sulfatoxymelatonin levels in patients with severe congestive heart failure

Objective: To assess urinary 6-sulfatoxymelatonin excretion in patients admitted to the hospital because of congestive heart failure (CHF). Methods: Urinary 6-sulfatoxymelatonin was measured by a specific radioimmunoassay in 33 hospitalized patients with CHF and in 146 healthy ambulatory volunteers. Individuals with hepatic or renal failure were excluded from the sample. Data were analyzed by the Mann-Whitney test and regression analysis. Results: 6-Sulfatoxymelatonin levels were significantly lower in CHF patients than controls (median 2.6 vs 6.02 µg, p<0.0001). This decrease was observed regardless of β-adrenergic blocker or benzodiazepine medication. A significant decrease in 6-sulfatoxymelatonin excretion occurred with age. There were no significant differences in urinary 6-sulfatoxymelatonin levels between chronic and acute CHF patients. Conclusions: The results suggest that circulating melatonin levels are low in patients with CHF. Such a decrease may precede aggravation of heart failure.