[Peculiarities of clinical picture of duodenal ulcer in the population of Northern Europe].

Duodenal ulcer remains a serious challenge to gastroenterology due to the difficulty of its management despite recent progress in this field. The role of melatonin in human body has attracted much attention of researchers in the recent years. Disturbances of its production are widely recognized to be involved in pathogenesis of duodenal ulcer and its exacerbation. This review summarizes results of research on the clinical picture of the disease in the population of European North where circadian and seasonal variations in melatonin production are most strongly pronounced.