RESUMO
BACKGROUND/AIMS: When stools containing altered blood are the sole evidence for acute gastrointestinal bleeding, the bleeding source is uncertain. Because the absorption of blood products via the small intestine is responsible for azotemia after gastrointestinal bleeding, patients with colorectal bleeding rarely become azotemic. Therefore the blood urea nitrogen to creatinine ratio (BUN/Cr ratio) is believed to reliably discriminate upper gastrointestinal bleeding (UGIB) from lower gastrointestinal bleeding (LGIB). This study was conducted to evaluate the BUN/Cr ratio for distinguishing an upper versus lower source of gastrointestinal bleeding. METHODS: Charts of patients who were admitted to Maryknoll hospital with the diagnosis of gastrointestinal bleeding from August 1994 to August 2000, were retrospectively reviewed for source of bleeding, initial blood urea nitrogen (BUN), creatinine (Cr), BUN/Cr ratio, hemoglobin, and hematocrit. RESULTS: A total of 298 patients were eligible for inclusion, 210 (70%) of whom were male. A total of 168 (56%) patients had an UGIB. Gastric ulcer disease (42%) and esophageal varices (27%) were the most common causes of UGIB, whereas malignant neoplasm was etiologic in 29% of LGIB episodes. The mean standard deviation BUN/Cr ratio was significantly higher in UGIB than LGIB (34.1+/-12.9 vs. 12.2+/-; p<01). CONCLUSIONS: The BUN/ Cr ratio may be a useful tool in distinguishing upper from lower sources of gastrointestinal bleeding, especially in patients with an uncertain source that could be upper or lower in origin.