Low urinary 6-sulphatoxymelatonin levels in patients with coronary artery disease

A decrease in nocturnal serum melatonin levels was reported in patients wit h clinically uncharacterized coronary artery disease. To assess whether the re was a correlation between melatonin production and disease stage, we mea sured the nocturnal urinary excretion of 6-sulphatoxymelatonin (an index of blood melatonin concentration) in patients with chronic stable or unstable coronary disease and in a group of age-matched controls. Three groups of i ndividuals were studied: a) 24 healthy subjects (mean age: 63 +/- 13 yr); b ) 32 patients with chronic, stable, coronary disease (62 +/- 11 yr); and c) 27 patients with unstable angina (62 +/- 12 yr). For 6-sulphatoxymelatonin measurement, urine was collected from 18:00 to 06:00 hr, within 48 hr of h ospitalization in the case of unstable angina. 6-Sulphatoxymelatonin was measured by a specific radioimmunoassay. Urinary 6-sulphatoxymelatonin excretion was significantly lower in unstable angina patients than in healthy subjects or in patients with stable angina. 6-Sulp hatoxymelatonin correlated negatively with age in healthy subjects, but not in coronary patients. 6-Sulphatoxymelatonin excretion in patients treated with beta-adrenoceptor blockers did not differ significantly from coronary patients not receiving beta-blockers. The results indicate that patients wi th coronary disease have a low melatonin production rate, with greater decr eases in those with higher risk of cardiac infarction and/or death.