Circadian variation in the time of onset of acute gastrointestinal bleeding.

The increased attention to biologic rhythms and clinical manifestations of several diseases has recently led to the identification of "chronorisks" for certain pathologic events. To evaluate whether a temporal pattern exists for acute gastrointestinal bleeding, 369 consecutive patients with acute gastrointestinal bleeding observed at the emergency department (ED) of S. Anna Hospital of Ferrara, Italy, during a 3-year period (1988-1990) were studied. On presentation to the ED, 287 patients had upper gastrointestinal tract bleeding (UGB), and 82 patients had lower gastrointestinal tract bleeding (LGB). In 270 cases of UGB and in 75 cases of LGB, the hour of symptom onset was known and the data were analyzed for the number of observed versus expected events during the four 6-hour intervals of a day. The majority of events occurred in the morning (32.2% of UGB and 42.7% of LGB). Cosinor analysis yielded a circadian rhythmicity with a peak in the late morning to early afternoon for both UGB and LGB independent of sex and site of bleeding.