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

AIM: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 in PDS 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:4.1-9.3) 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.