Abstract
AIM: To examine characteristics of patients with blood urea nitrogen (BUN) levels higher and lower than the normal limit.
METHODS: Patient records between April 2011 and March 2014 were analyzed retrospectively. During this time, 3296 patients underwent upper endoscopy. In total, 50 male (69.2 ± 13.2 years) and 26 female (72.3 ± 10.2 years) patients were assessed. Patients were divided into two groups based on BUN levels: higher than the normal limit (21.0 mg/dL) (H) and lower than the normal limit (L). One-way analysis of variance was performed to reveal differences in the variables between the H and L groups. Fisher’s exact test was used to compare the percentage of patients with gastric ulcer or gastric cancer in the H and L groups.
RESULTS: White blood cell count was higher in the H group than in the L group (P = 0.0047). Hemoglobin level was lower in the H group than in the L group (P = 0.0307). Glycated hemoglobin was higher in the H group than in the L group (P = 0.0264). The percentage of patients with gastric ulcer was higher in the H group (P = 0.0002). The H group contained no patients with gastric cancer.
CONCLUSION: Patients with BUN ≥ 21 mg/dL might have more severe upper gastrointestinal bleeding.
Keywords: Blood urea nitrogen, Forrest classification, Hemoglobin, White blood cell count
Core tip: Blood urea nitrogen (BUN) is a useful predictor of upper gastrointestinal (GI) bleeding. However, BUN is within the normal range in some patients with upper GI bleeding. Patient records were analyzed retrospectively. Patients were divided into two groups: higher than the normal limit (21.0 mg/dL) (H) and lower than the normal limit (L). White blood cell count was higher and hemoglobin was lower in the H group. Higher BUN was associated with severe upper GI bleeding. The H group suggested more severe upper GI bleeding.
INTRODUCTION
Upper gastrointestinal (GI) bleeding is defined as bleeding that occurs proximal to the ligament of Treitz. Causes of upper GI bleeding include gastric ulcers, duodenal ulcers, and gastric cancer[1]. The mortality rate of upper GI bleeding ranges from 3.5% to 7.4%[2,3]. Upper GI bleeding is diagnosed with endoscopy, and treated using methods such as clipping and bipolar electrocoagulation[4]. When patients do not respond to these therapies, arteriography with embolization is performed[5,6]. Although treatment methods have improved, the mortality rate is 40% for patients with GI bleeding who are hemodynamically unstable[7]. Accurate diagnosis of upper or lower GI bleeding is important because early endoscopy significantly reduces mortality rates[8]. Blood testing is recommended before upper GI endoscopy or colonoscopy is performed because of the low cost and minimal risks of complications[9].
Blood urea nitrogen (BUN) is a measure of the amount of urea nitrogen in the blood[10]. BUN represents the terminal products of protein metabolism via ammonia[11]. When upper GI bleeding occurs, the blood is digested to protein[12]. This protein is transported to the liver via the portal vein, and metabolized to BUN in the urea cycle[13]. Higher BUN values are therefore associated with the digestion of blood[14]. Mean BUN is 37.7 ± 26.4 g/mL in patients with upper GI bleeding who need blood transfusion and admission to intensive care[15]. BUN is not as useful as reduced hemoglobin (Hb) level for predicting upper GI bleeding[16].
In this study, we compared the characteristics of patients with upper GI bleeding and BUN higher or lower than the upper normal limit to determine the reason for the difference between the two groups.
MATERIALS AND METHODS
Patients
Patient records between April 2011 and March 2014 were analyzed retrospectively. Patients were divided into two groups: those with BUN higher than the normal limit (21.0 mg/dL) (H), and those with BUN lower than the normal limit (L). Gastric or duodenal ulcer bleeding was defined as coming from either a spurting vessel (1a), an oozing vessel (1b), a visible vessel (2a), or a clot (2b) according to the Forrest classification system[17]. Our study was reviewed by our institutional Ethics Committee and was not designated as a clinical trial because it was performed as part of routine clinical practice. Patient anonymity was maintained.
Upper GI endoscopy and colonoscopy
Patients received an upper GI endoscopic examination for screening, examination of abdominal symptoms, or anemia. The endoscopic devices used were the GIF-N260H, GIF-XP260NS, GIF-PG260, GIF-XQ260, and GIF-Q260 (Olympus Corp., Tokyo, Japan).
Blood test variables
The blood test variables analyzed were white blood cell (WBC) count, Hb, C-reactive protein, platelet, total protein, albumin, total bilirubin, alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase, gamma-glutamyl transpeptidase, lactate dehydrogenase, uric acid, BUN, creatinine (Cre), total cholesterol, triglycerides, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, blood glucose, glycated Hb (HbA1c), body mass index, carcinoembryonic antigen, and carbohydrate antigen 19-9.
Statistical analysis
One-way analysis of variance was performed to reveal differences in the variables between the H and L groups, and between patients for whom BUN was examined and those for whom it was not. Logistic regression analysis was performed to reveal variables that were significantly associated with the difference between the H and L groups. Fisher’s exact test was used to compare the percentage of patients with gastric ulcer or gastric cancer in the H and L groups. Pearson’s χ2 test was applied to assess the correlation in percentage of different Forrest classifications in the H and L groups. A P < 0.05 indicated statistical significance. JMP 10.0.2 software (SAS Institute, Cary, NC, United States) was used for all statistical analyses.
RESULTS
During this time, 3296 patients underwent upper GI endoscopy. In total, 50 male (69.2 ± 13.2 years) and 26 female (72.3 ± 10.2 years) patients were identified with upper GI bleeding. The etiologies of upper GI bleeding in these patients are listed in Table 1. Patient characteristics were compared to determine the variables affecting the differences between the H and L groups (Table 2). WBC was higher in the H group than in the L group (P < 0.05). Hb level was lower in the H group than in the L group (P < 0.05). BUN and BUN/Cre ratio were both higher in the H group than in the L group (P < 0.05). These results were expected because the two groups were divided based on BUN. Cre was higher in the H group than in the L group (P < 0.05). HbA1c was higher in the H group than in the L group (P < 0.05). The lower Hb level in the H group suggested that the H group contained patients with more severe bleeding. One major difference between the H group and the L group was the cause of the upper GI bleeding. The H group had no patients with gastric cancer.
Table 1.
Causes of upper gastrointestinal bleeding in this study
| Cause | Total (n) | BUN analyzed (n) |
| Gastric ulcer | 31 | 29 |
| Gastric cancer | 28 | 18 |
| Duodenal ulcer | 7 | 3 |
| Acute gastric mucosal lesion | 4 | 1 |
| Esophageal ulcer | 2 | 1 |
| Esophageal varix | 2 | 2 |
| Esophagitis | 1 | 1 |
| Gastric invasion of pancreatic cancer | 1 | 1 |
| Total | 76 | 56 |
BUN: Blood urea nitrogen.
Table 2.
Comparison of variables between patients with blood urea nitrogen higher and lower than 21.0 mg/dL
| Variable | No. of patients | H group (n = 20) | L group (n = 36) | P value |
| Age (yr) | 56 | 69.7 ± 17.3 | 71.1 ± 9.4 | 0.7040 |
| WBC (102/μL) | 56 | 9575 ± 5088 | 6700 ± 2187 | 0.0047 |
| Hb (g/dL) | 56 | 8.64 ± 3.47 | 10.6 ± 3.09 | 0.0307 |
| CRP (mg/dL) | 39 | 1.66 ± 2.03 | 0.99 ± 0.85 | 0.1557 |
| Plt (104/μL) | 54 | 23.1 ± 8.4 | 29.4 ± 12.8 | 0.0629 |
| TP (g/dL) | 35 | 5.70 ± 0.98 | 6.20 ± 0.68 | 0.0874 |
| Alb (g/dL) | 36 | 3.32 ± 0.69 | 3.53 ± 0.62 | 0.3546 |
| T-Bil (mg/dL) | 44 | 0.62 ± 0.40 | 0.71 ± 0.63 | 0.6461 |
| ALP (IU/L) | 32 | 178 ± 53 | 260 ± 159 | 0.1449 |
| AST (IU/L) | 51 | 23.7 ± 12.0 | 27.1 ± 25.3 | 0.6062 |
| ALT (IU/L) | 53 | 25.9 ± 26.0 | 18.0 ± 14.9 | 0.1654 |
| γ-GTP (IU/L) | 29 | 22.6 ± 14.3 | 82.8 ± 107 | 0.2031 |
| LDH (IU/L) | 15 | 42.7 ± 6.6 | 46.0 ± 10.8 | 0.6261 |
| UA (mg/dL) | 24 | 5.84 ± 2.47 | 5.00 ± 1.93 | 0.3638 |
| BUN (mg/dL) | 56 | 36.3 ± 17.3 | 12.3 ± 3.8 | < 0.0001 |
| Cre (mg/dL) | 56 | 1.09 ± 0.37 | 0.83 ± 0.32 | 0.0086 |
| BUN/Cre | 56 | 35.0 ± 13.2 | 16.1 ± 6.3 | < 0.0001 |
| T-Chol (mg/dL) | 21 | 143 ± 37 | 145 ± 47 | 0.9102 |
| TG (mg/dL) | 16 | 98 ± 68 | 101 ± 48 | 0.9408 |
| HDL (mg/dL) | 15 | 42.7 ± 6.6 | 46.0 ± 10.8 | 0.6261 |
| LDL (mg/dL) | 14 | 72.7 ± 38.4 | 95.5 ± 30.5 | 0.2954 |
| BG (mg/dL) | 32 | 164 ± 92 | 121 ± 34 | 0.0622 |
| HbA1c (%) | 21 | 6.31 ± 1.04 | 5.54 ± 0.46 | 0.0264 |
H group: Patients with BUN > 21.0 mg/dL; L group: Patients with BUN < 21.0 mg/dL; WBC: White blood cell count; Hb: Hemoglobin; CRP: C-reactive protein; Plt: Platelet; TP: Total protein; Alb: Albumin; T-Bil: Total bilirubin; ALP: Alkaline phosphatase; AST: Aspartate aminotransferase; ALT: Alanine aminotransferase; γ-GTP: Gamma-glutamyl transpeptidase; LDH: Lactate dehydrogenase; UA: Uric acid; BUN: Blood urea nitrogen; Cre: Creatinine; T-Chol: Total cholesterol; TG: Triglyceride; HDL: High-density lipoprotein cholesterol; LDL: Low-density lipoprotein cholesterol; BG: Blood glucose; HbA1c: Glycated hemoglobin.
There might be biases regarding the physicians’ decisions to examine BUN. To analyze the potential biases, patient characteristics were compared between patients with upper GI bleeding (n = 76) for whom BUN was or was not examined (Table 3). All the variables showed no significant difference except total cholesterol (P < 0.05).
Table 3.
Comparison of variables between patients examined for blood urea nitrogen or not
| Variable | No. of patients | BUN examined group (n = 56) | BUN not examined group (n = 20) | P value |
| Age (yr) | 76 | 70.6 ± 1.7 | 69.9 ± 2.8 | 0.8353 |
| WBC (102/μL) | 68 | 7726 ± 3731 | 6266 ± 1624 | 0.1905 |
| Hb (g/dL) | 68 | 9.92 ± 3.34 | 10.8 ± 2.39 | 0.3817 |
| CRP (mg/dL) | 46 | 1.22 ± 1.40 | 2.21 ± 1.66 | 0.1024 |
| Plt (104/μL) | 65 | 27.2 ± 11.8 | 27.9 ± 8.1 | 0.8639 |
| TP (g/dL) | 43 | 5.96 ± 0.86 | 6.44 ± 0.69 | 0.1513 |
| Alb (g/dL) | 38 | 3.48 ± 0.64 | 2.95 ± 0.64 | 0.2851 |
| T-Bil (mg/dL) | 46 | 0.68 ± 0.58 | 0.87 ± 0.11 | 0.6543 |
| ALP (IU/L) | 34 | 236 ± 142 | 232 ± 89 | 0.9649 |
| AST (IU/L) | 58 | 26.1 ± 21.9 | 19.6 ± 3.8 | 0.4409 |
| ALT (IU/L) | 62 | 20.7 ± 19.5 | 17.6 ± 6.46 | 0.6379 |
| γ-GTP (IU/L) | 33 | 59.0 ± 93.8 | 37.0 ± 16.8 | 0.6477 |
| LDH (IU/L) | 45 | 187 ± 55 | 195 ± 36 | 0.7244 |
| UA (mg/dL) | 29 | 5.32 ± 2.13 | 5.00 ± 0.77 | 0.7459 |
| Cre (mg/dL) | 64 | 0.92 ± 0.36 | 0.94 ± 0.28 | 0.9148 |
| T-Chol (mg/dL) | 28 | 144 ± 41 | 202 ± 31 | 0.0018 |
| BG (mg/dL) | 36 | 134 ± 61 | 117 ± 8 | 0.5669 |
WBC: White blood cell count, Hb: Hemoglobin; CRP: C-reactive protein; Plt: Platelet; TP: Total protein; Alb: Albumin; T-Bil: Total bilirubin; ALP: Alkaline phosphatase; AST: Aspartate aminotransferase; ALT: Alanine aminotransferase; γ-GTP: Gamma-glutamyl transpeptidase; LDH: Lactate dehydrogenase; UA: Uric acid; Cre: Creatinine; T-Chol: Total cholesterol; BG: Blood glucose.
To clarify the strength of the association between the H and L groups in the blood test parameters, logistic regression analysis was performed (Table 4). Hb had the largest χ2 value and the smallest P value (P < 0.05).
Table 4.
Results of logistic regression analysis
| Variable | χ2 | Odds | P value |
| WBC | 0.10 | 0.999918 | 0.7471 |
| Hb | 6.36 | 0.545371 | 0.0116 |
| Cre | 3.31 | 489.6214 | 0.0688 |
| HbA1c | 4.73 | 13.58043 | 0.0296 |
WBC: White blood cell count; Hb: Hemoglobin; Cre: Creatinine; HbA1c: Glycated hemoglobin.
Most of the enrolled patients had gastric cancer or gastric ulcers. The percentage of patients with gastric cancer or gastric ulcer was compared between the H and L groups (Table 5). There were no patients with gastric cancer in the H group.
Table 5.
Association of blood urea nitrogen and gastric ulcer or cancer
| Group | Gastric ulcer | Gastric cancer | Total | |
| BUN1 (mg/dL) | ≥ 21.0 | 15 | 0 | 15 |
| < 21.0 | 14 | 18 | 32 | |
| Total | 29 | 18 | 47 | |
P = 0.0002 between groups via Fisher’s exact probability test. BUN: Blood urea nitrogen.
The association between different Forrest classifications and the two groups was intriguing. A χ2 test was performed to reveal the association (Table 6), and no statistically significant relationship was found.
Table 6.
Association of blood urea nitrogen and Forrest classification
| Group | 1b | 2a | 2b | Total | |
| BUN1 (mg/dL) | ≥ 21.0 | 5 | 7 | 3 | 15 |
| < 21.0 | 4 | 5 | 5 | 14 | |
| Total | 9 | 12 | 8 | 29 | |
P = 0.6322 between groups via χ2 test. BUN: Blood urea nitrogen.
DISCUSSION
Higher BUN is associated with upper GI bleeding[18]. Lower Hb level is associated with the severity of upper GI bleeding[16]. It is speculated that higher BUN has a strong association with lower Hb, however, there is no direct evidence for this. In the present study, the Hb level was lower in the H group than in the L group. Logistic regression analysis clearly showed that the strongest association was between higher BUN and lower Hb. These results indicate that bleeding was more severe in the H group than the L group. It was speculated that larger amounts of Hb in the digestive tract are the source of higher BUN in blood. This hypothesis was supported by the fact that ammonia is liberated from Hb in the digestive tract[19].
Elevated WBC is associated with the severity and mortality rate of upper GI bleeding[20]. Patients with a WBC > 12000/μL need urgent upper GI endoscopy[21]. In the present study, WBC was higher in the H group than in the L group. One reason for elevated WBC is inflammation[22]. Gastric ulceration is a form of inflammation similar to inflammatory bowel disease[23]. Elevation of WBC was, therefore, associated with the severity of upper GI bleeding. Our results and the previous reports support the hypothesis that higher BUN is associated with the severity of upper GI bleeding.
A BUN/Cre ratio > 30 is a useful metric by which to diagnose upper GI bleeding[24]. The association between elevated BUN/Cre and upper GI bleeding has previously been made clear with Tc-99m-labeled red blood cells[25]. On the other hand, Chalasani et al[26] reported that BUN/Cre is not always reliable for diagnosing upper GI bleeding. They speculated that BUN/Cre does not increase without hematemesis. Akimoto et al[27] added that BUN/Cre is elevated due to reduced hydration. In some cases, elevated BUN is indeed a consequence of upper GI bleeding and hypovolemia[14]. In the present study, BUN and BUN/Cre were strongly correlated. Together, these data suggest that BUN might be within the normal range in some patients with upper GI bleeding.
One limitation of the present study is that it included a limited number of patients with more severe bleeding, such as the spurting type. Although without statistical significance, 1b and 2a were more frequent in the H group than in the L group. With more patients, there is the possibility Forrest classification might correlate with BUN.
Another limitation is that the study was retrospective. Determination of choice of blood variables depended upon the physicians. This was the reason that some data of blood variables were missing. There might be a selection bias in patient characteristics between those with BUN and those without BUN, although Table 3 did not show significant statistical significance.
In conclusion, patients with BUN ≥ 21 mg/dL might have more severe upper GI bleeding. It is recommended that severe upper GI bleeding be considered when BUN is higher than 21.0 mg/dL.
COMMENTS
Background
Upper gastrointestinal (GI) bleeding is defined as bleeding that occurs proximal to the ligament of Treitz. Causes of upper GI bleeding include gastric ulcers, duodenal ulcers, and gastric cancer. Although treatment methods have improved, the mortality rate is 40% for patients with GI bleeding who are hemodynamically unstable. Accurate diagnosis of upper GI bleeding is important because early endoscopy significantly reduces mortality rates. Blood testing is recommended before upper GI endoscopy or colonoscopy is performed because of the low cost and minimal risks of complications.
Research frontiers
Blood urea nitrogen (BUN) represents the terminal products of protein metabolism via ammonia. When upper GI bleeding occurs, the blood is digested to protein metabolized to BUN in the urea cycle within the liver. Higher BUN values are therefore associated with the digestion of blood. Mean BUN is 37.7 ± 26.4 g/mL in patients with upper GI bleeding who need blood transfusion and admission to intensive care. Lower hemoglobin (Hb) is associated with GI bleeding. Direct association between Hb and BUN has not been clear in upper GI bleeding.
Innovations and breakthroughs
Patients were divided into two groups: the H group with BUN > 21.0 mg/dL, and the L group with BUN < 21.0 mg/dL. Patient characteristics were compared between the H group and the L group. White blood cell count was higher in the H group. Hb was lower in the H group. Logistic regression analysis was performed to investigate what variables are associated with BUN. Hb had the strongest association with BUN. Low Hb was associated with the severity of the upper GI bleeding. These results suggest that patients with BUN > 21.0 mg/dL have more severe upper GI bleeding.
Applications
Patients with BUN ≥ 21 mg/dL might have more severe upper GI bleeding. It is recommended that severe upper GI bleeding be considered when BUN is higher than 21.0 mg/dL.
Peer-review
This study examines variables associated with higher than normal BUN levels and GI bleeding. The results show that patients with high BUN have higher WBC counts and lower Hb, suggestive of more severe GI bleeding.
Footnotes
Ethics approval: The study was reviewed and approved by the National Hospital Organization Shimoshizu Hospital Institutional Review Board.
Informed consent: All study participants, or their legal guardian, provided informed written consent prior to study enrollment.
Conflict-of-interest: The authors declare no conflicts of interest.
Data sharing: No additional data are available.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Peer-review started: December 8, 2014
First decision: January 22, 2015
Article in press: March 19, 2015
P- Reviewer: Olaussen A S- Editor: Yu J L- Editor: AmEditor E- Editor: Zhang DN
References
- 1.Theocharis GJ, Thomopoulos KC, Sakellaropoulos G, Katsakoulis E, Nikolopoulou V. Changing trends in the epidemiology and clinical outcome of acute upper gastrointestinal bleeding in a defined geographical area in Greece. J Clin Gastroenterol. 2008;42:128–133. doi: 10.1097/01.mcg.0000248004.73075.ad. [DOI] [PubMed] [Google Scholar]
- 2.Hearnshaw SA, Logan RF, Lowe D, Travis SP, Murphy MF, Palmer KR. Acute upper gastrointestinal bleeding in the UK: patient characteristics, diagnoses and outcomes in the 2007 UK audit. Gut. 2011;60:1327–1335. doi: 10.1136/gut.2010.228437. [DOI] [PubMed] [Google Scholar]
- 3.Leontiadis GI, Molloy-Bland M, Moayyedi P, Howden CW. Effect of comorbidity on mortality in patients with peptic ulcer bleeding: systematic review and meta-analysis. Am J Gastroenterol. 2013;108:331–45; quiz 346. doi: 10.1038/ajg.2012.451. [DOI] [PubMed] [Google Scholar]
- 4.Kim SY, Hyun JJ, Jung SW, Lee SW. Management of non-variceal upper gastrointestinal bleeding. Clin Endosc. 2012;45:220–223. doi: 10.5946/ce.2012.45.3.220. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 5.Wilkins T, Khan N, Nabh A, Schade RR. Diagnosis and management of upper gastrointestinal bleeding. Am Fam Physician. 2012;85:469–476. [PubMed] [Google Scholar]
- 6.Katano T, Mizoshita T, Senoo K, Sobue S, Takada H, Sakamoto T, Mochiduki H, Ozeki T, Kato A, Matsunami K, et al. The efficacy of transcatheter arterial embolization as the first-choice treatment after failure of endoscopic hemostasis and endoscopic treatment resistance factors. Dig Endosc. 2012;24:364–369. doi: 10.1111/j.1443-1661.2012.01285.x. [DOI] [PubMed] [Google Scholar]
- 7.Walsh RM, Anain P, Geisinger M, Vogt D, Mayes J, Grundfest-Broniatowski S, Henderson JM. Role of angiography and embolization for massive gastroduodenal hemorrhage. J Gastrointest Surg. 1999;3:61–5; discussion 66. doi: 10.1016/s1091-255x(99)80010-9. [DOI] [PubMed] [Google Scholar]
- 8.Peura DA, Lanza FL, Gostout CJ, Foutch PG. The American College of Gastroenterology Bleeding Registry: preliminary findings. Am J Gastroenterol. 1997;92:924–928. [PubMed] [Google Scholar]
- 9.Sonnenberg A. Test sequence in the management of gastrointestinal bleeding. Endoscopy. 2012;44:43–47. doi: 10.1055/s-0031-1291536. [DOI] [PubMed] [Google Scholar]
- 10.Schutz Y. Protein turnover, ureagenesis and gluconeogenesis. Int J Vitam Nutr Res. 2011;81:101–107. doi: 10.1024/0300-9831/a000064. [DOI] [PubMed] [Google Scholar]
- 11.Adeva MM, Souto G, Blanco N, Donapetry C. Ammonium metabolism in humans. Metabolism. 2012;61:1495–1511. doi: 10.1016/j.metabol.2012.07.007. [DOI] [PubMed] [Google Scholar]
- 12.Mardini H, Record C. Pathogenesis of hepatic encephalopathy: lessons from nitrogen challenges in man. Metab Brain Dis. 2013;28:201–207. doi: 10.1007/s11011-012-9362-2. [DOI] [PubMed] [Google Scholar]
- 13.Häberle J. Clinical and biochemical aspects of primary and secondary hyperammonemic disorders. Arch Biochem Biophys. 2013;536:101–108. doi: 10.1016/j.abb.2013.04.009. [DOI] [PubMed] [Google Scholar]
- 14.Stellato T, Rhodes RS, McDougal WS. Azotemia in upper gastrointestinal hemorrhage. A review. Am J Gastroenterol. 1980;73:486–489. [PubMed] [Google Scholar]
- 15.Al-Naamani K, Alzadjali N, Barkun AN, Fallone CA. Does blood urea nitrogen level predict severity and high-risk endoscopic lesions in patients with nonvariceal upper gastrointestinal bleeding? Can J Gastroenterol. 2008;22:399–403. doi: 10.1155/2008/207850. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 16.Tomizawa M, Shinozaki F, Hasegawa R, Togawa A, Shirai Y, Ichiki N, Motoyoshi Y, Sugiyama T, Yamamoto S, Sueishi M. Reduced hemoglobin and increased C-reactive protein are associated with upper gastrointestinal bleeding. World J Gastroenterol. 2014;20:1311–1317. doi: 10.3748/wjg.v20.i5.1311. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 17.Forrest JA, Finlayson ND, Shearman DJ. Endoscopy in gastrointestinal bleeding. Lancet. 1974;2:394–397. doi: 10.1016/s0140-6736(74)91770-x. [DOI] [PubMed] [Google Scholar]
- 18.González-González JA, García-Compean D, Vázquez-Elizondo G, Garza-Galindo A, Jáquez-Quintana JO, Maldonado-Garza H. Nonvariceal upper gastrointestinal bleeding in patients with liver cirrhosis. Clinical features, outcomes and predictors of in-hospital mortality. A prospective study. Ann Hepatol. 2011;10:287–295. [PubMed] [Google Scholar]
- 19.van Berlo CL, van de Bogaard AE, van der Heijden MA, van Eijk HM, Janssen MA, Bost MC, Soeters PB. Is increased ammonia liberation after bleeding in the digestive tract the consequence of complete absence of isoleucine in hemoglobin? A study in pigs. Hepatology. 1989;10:315–323. doi: 10.1002/hep.1840100311. [DOI] [PubMed] [Google Scholar]
- 20.Weng SC, Shu KH, Tarng DC, Tang YJ, Cheng CH, Chen CH, Yu TM, Chuang YW, Huang ST, Sheu WH, et al. In-hospital mortality risk estimation in patients with acute nonvariceal upper gastrointestinal bleeding undergoing hemodialysis: a retrospective cohort study. Ren Fail. 2013;35:243–248. doi: 10.3109/0886022X.2012.747140. [DOI] [PubMed] [Google Scholar]
- 21.Adamopoulos AB, Baibas NM, Efstathiou SP, Tsioulos DI, Mitromaras AG, Tsami AA, Mountokalakis TD. Differentiation between patients with acute upper gastrointestinal bleeding who need early urgent upper gastrointestinal endoscopy and those who do not. A prospective study. Eur J Gastroenterol Hepatol. 2003;15:381–387. doi: 10.1097/00042737-200304000-00008. [DOI] [PubMed] [Google Scholar]
- 22.Abramson N, Melton B. Leukocytosis: basics of clinical assessment. Am Fam Physician. 2000;62:2053–2060. [PubMed] [Google Scholar]
- 23.Arakawa T, Watanabe T, Tanigawa T, Tominaga K, Fujiwara Y, Morimoto K. Quality of ulcer healing in gastrointestinal tract: its pathophysiology and clinical relevance. World J Gastroenterol. 2012;18:4811–4822. doi: 10.3748/wjg.v18.i35.4811. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 24.Srygley FD, Gerardo CJ, Tran T, Fisher DA. Does this patient have a severe upper gastrointestinal bleed? JAMA. 2012;307:1072–1079. doi: 10.1001/jama.2012.253. [DOI] [PubMed] [Google Scholar]
- 25.Lewis DH, Jacobson AF. BUN/creatinine ratios: aid to decision making about delayed imaging in Tc-99m red blood cell scans for gastrointestinal hemorrhage. Clin Nucl Med. 1998;23:201–204. doi: 10.1097/00003072-199804000-00001. [DOI] [PubMed] [Google Scholar]
- 26.Chalasani N, Clark WS, Wilcox CM. Blood urea nitrogen to creatinine concentration in gastrointestinal bleeding: a reappraisal. Am J Gastroenterol. 1997;92:1796–1799. [PubMed] [Google Scholar]
- 27.Akimoto T, Ito C, Kato M, Ogura M, Muto S, Kusano E. Reduced hydration status characterized by disproportionate elevation of blood urea nitrogen to serum creatinine among the patients with cerebral infarction. Med Hypotheses. 2011;77:601–604. doi: 10.1016/j.mehy.2011.06.044. [DOI] [PubMed] [Google Scholar]