Secretion of melatonin and 6-sulfatoxymelatonin urinary excretion in functional dyspepsia

To evaluate blood concentration of melatonin and urinary excretion of its metabolite, 6-sulfatoxymelatonin （6-OHMS）, in functional dyspepsia （FD）. METHODS： Ninety individuals were enrolled in the study： 30 in each study group： patients with postprandial distress syndrome （PDS）, epigastric pain syndrome （EPS）, and controls. Blood samples were drawn at 02：00 and 09：00 h and 24-h urine collection was performed. Serum melatonin and urinary 6-OHMS concentrations were measured by enzyme-linked immunosorbent assay. RESULTS： Serum melatonin concentration at night and in the morning was significantly （P 〈 0.001） higher inPDS patients [at 02：00 h-93.3 pg/mL, quartile range （QR）： 79.8-116.2; at 09.00 h-14.3 pg/mL, QR： 7.06-19.0] than in EPS （57.2 pg/mL, QR： 42.6-73.1, 8.1 pg/mL, QR： 4.2-9.3） and control patients （57.7 pg/mL, QR： 51.2-62.5; 8.1 pg/mL, QR： 5.4-10.3）. A similar relationship was observed for urinary 6-OHMS excretion. Patients with severe PDS symptoms had a higher melatonin concentration than these with moderate syndromes, whereas patients with severe EPS had a lower urinary 6-OHMS excretion than patients with moderate symptoms.CONCLUSION： Evaluation of melatonin serum concentrations and 24-h urinary 6-OHMS excretion are useful methods for differential diagnosis of various clinical forms of FD.