Abstract: Objective: By analyzing the changes of blood urea nitrogen/creatinine（BUN/Cr）ratio in patients with gastrointestinal
bleeding, the best diagnostic cutoff point was found to identify the BUN/Cr value of upper and lower gastrointestinal bleeding.
Methods: The patients in the emergency department of gastrointestinal bleeding admitted to the People′s Hospital of Yuxi City from
January 2015 to December 2016 were reviewed and collected, including information on vital signs, age and gender detected at the time
of admission. The BUN/Cr differential analysis was performed by calculating the BUN/Cr value of the patient and dividing the bleeding
site into the upper gastrointestinal bleeding group and the lower gastrointestinal bleeding group. Results: A total of 120 patients with
gastrointestinal bleeding were enrolled, including 72 cases of upper gastrointestinal bleeding and 48 cases of lower gastrointestinal
bleeding. The BUN/Cr value of the upper gastrointestinal bleeding group was higher than that of the lower gastrointestinal bleeding
group（P<0.05）. When the BUN/Cr value was ≥ 28.5, upper gastrointestinal bleeding was considered, the sensitivity was 76.1%, and
the specificity was 89.2%. Conclusion: BUN/Cr value ≥ 28.50 has a higher value for the diagnosis of upper gastrointestinal bleeding;
and BUN/Cr value < 28.50 cannot identify upper and lower gastrointestinal bleeding.

Key words: blood urea nitrogen/creatinine ratio, upper and lower gastrointestinal bleeding, diagnosis