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Usefulness of the blood urea nitrogen/creatinine ratio in gastrointestinal bleeding
A A Ernst1, M L Haynes, T G Nick
1Department of Emergency Medicine, Vanderbilt University, Nashville, TN, USA.
Insights
The blood urea nitrogen/creatinine (BUN/Cr) ratio can help identify upper gastrointestinal (GI) bleeding sources. A BUN/Cr ratio over 36 shows high sensitivity for upper GI bleeding.
Area of Science:
- Gastroenterology
- Internal Medicine
- Emergency Medicine
Background:
- Gastrointestinal (GI) bleeding is a common medical emergency.
- Differentiating upper from lower GI bleeding sources is crucial for timely and appropriate management.
- The blood urea nitrogen/creatinine (BUN/Cr) ratio is a readily available laboratory marker.
Purpose of the Study:
- To evaluate the utility of the BUN/Cr ratio in distinguishing upper from lower GI bleeding.
- To determine the sensitivity and specificity of the BUN/Cr ratio for identifying upper GI bleeding.
Main Methods:
- Retrospective chart review of 124 patients presenting to the emergency department with GI bleeding.
- Data collected included BUN, creatinine, BUN/Cr ratio, hematocrit, and bleeding source.
- Statistical analysis, including receiver operating characteristic (ROC) curve analysis, was performed.
Main Results:
- A total of 124 patients were included; 70% had upper GI bleeding.
- The BUN/Cr ratio showed a significant correlation with an upper GI source of bleeding (P = .03) after accounting for age and gender.
- A BUN/Cr ratio greater than 36 demonstrated 90% sensitivity and 27% specificity for upper GI bleeding.
Conclusions:
- The BUN/Cr ratio, particularly when greater than 36, is a valuable tool for suggesting an upper GI bleeding source.
- Incorporating age and gender with the BUN/Cr ratio improves diagnostic accuracy for GI bleeding location.
- Further prospective studies may validate these findings in diverse patient populations.
Abstract:
This study was conducted to evaluate the blood urea nitrogen/creatinine (BUN/Cr) ratio for distinguishing an upper versus lower source of gastrointestinal (GI) bleeding. Charts of patients who presented to the emergency department (ED) with the diagnosis of GI bleeding from August 1995 to August 1996 were retrospectively reviewed for source of bleeding, initial BUN, Cr, BUN/Cr ratio, hematocrit (Hct), and need for transfusion. A total of 124 patients were eligible for inclusion, 71 (57%) of whom were male. A total of 63 (51%) presented with blood in stool and 53 (43%) with bloody emesis; 8 (6%) had blood in both emesis and stool. A total of 31 (25%) patients had a lower GI bleed, 88 (70%) had an upper, and 5 (4%) had both upper and lower bleeding sources. The mean BUN level was 24 mg/dL, the mean Cr level 1.03 mg/dL, and the mean BUN/Cr ratio was 24. The mean hemoglobin (Hb) level was 11.3 g/dL, the mean Hct was 32 g/dL, and 51% required transfusion. Upper GI bleeding was significantly correlated with age younger than 50 (P = .01) and male gender (P = .01; odds ratio, 3.13). Taking into account age and gender, the BUN/Cr ratio correlated significantly with an upper GI source of bleeding (P = .03), with a ratio greater than 36 having a sensitivity of 90% and a specificity of 27%. The area under the receiver operating characteristic curve using age, gender, and BUN/Cr ratio was .73 (95% confidence interval, .62 to .84).