Abstract
BACKGROUND AND AIMS: Melatonin is a hormone released from the pineal gland and enterochromaffin cells of the gastrointestinal tract. The influence of melatonin on gastric pathologies is not fully investigated. Our aim was to evaluate the relationship between fasting gastric juice melatonin levels and gastroduodenal pathologies among Zambian patients. METHODS: This cross-sectional study was conducted in Lusaka, Zambia. We collected morning fasting gastric juice samples from patients presenting for oesophagogastroduodenoscopy (OGD) to quantify levels of melatonin using commercial ELISA kits. Interviewer administered questionnaires were used to collect baseline characteristics. Data were analyzed in Stata version 15. RESULTS: We collected gastric juice from 175 patients with a median age of 49 years, IQR (40-65). The number of females was 95 (54%) and males 80 (46%). Of these, 100 (57%) had normal OGD examinations, 49 (28%) peptic ulcers, 25 (14%) gastric cancer and 1 (1%) gastric polyp. The median level of melatonin in normal patients was 141.8 pg/mL, IQR (46.2-500.1). In those with gastroduodenal pathologies, the median was 339.4 pg/mL, IQR (101.8-500.1) and the difference was statistically significant, p = 0.02. Results also revealed significantly higher levels of melatonin among patients with history of cigarette smoking, p = 0.003. CONCLUSION: There is an association between gastroduodenal pathology and morning gastric juice melatonin levels, a finding whose biological significance warrants further research.