What is the diagnosis for a male patient with hematemesis, mild anemia, and elevated blood urea level, with otherwise normal labs and a normal past medical history?

Diagnosis: Peptic Ulcer Disease (Option C)

The most likely diagnosis is peptic ulcer disease (PUD), as the combination of hematemesis with elevated blood urea nitrogen (BUN) and mild anemia in a patient with otherwise normal labs strongly suggests upper gastrointestinal bleeding from a peptic ulcer. 1, 2

Key Diagnostic Features

Elevated BUN as a Discriminator

• The elevated BUN level is the critical diagnostic clue that distinguishes upper GI bleeding from lower GI sources 1
• The BUN/creatinine ratio is significantly higher in upper GI bleeding (mean 22.5 ± 11.5) compared to lower GI bleeding (15.9 ± 8.2) 1
• Elevated BUN occurs because blood proteins are digested in the upper GI tract and absorbed, increasing urea production 1
• Patients with BUN ≥21 mg/dL typically have more severe upper GI bleeding 2

Clinical Presentation Pattern

• Hematemesis definitively localizes bleeding to the upper GI tract 3
• Mild anemia (rather than severe) with hematemesis suggests ongoing or recent bleeding rather than massive acute hemorrhage 3
• Normal past medical history makes chronic conditions less likely 3

Why Peptic Ulcer Disease is Most Likely

Epidemiological Support

• Peptic ulcer disease accounts for 57% of upper GI bleeding cases, making it the most common cause 1
• PUD commonly presents with occult bleeding leading to anemia and elevated BUN 3
• The combination of hematemesis with mild anemia is characteristic of peptic ulcer bleeding 4

Distinguishing from Other Options

Mallory-Weiss Syndrome (Option A):

• Typically presents with hematemesis following forceful vomiting or retching 3
• The question states "normal past medical history" without mention of preceding vomiting episodes
• Less likely to cause the degree of BUN elevation seen with peptic ulcers 1

Erosive Gastritis (Option B):

• While erosive gastritis can cause upper GI bleeding, it is less common than PUD as a cause of significant bleeding requiring medical attention 3
• Erosive gastritis typically causes less severe bleeding and would be less likely to produce marked BUN elevation 3
• The clinical presentation with hematemesis and elevated BUN suggests a more substantial bleeding source 2

Clinical Correlation

Laboratory Pattern

• White blood cell count may be elevated in peptic ulcer bleeding 2
• Hemoglobin levels are reduced proportional to blood loss 2
• The elevated BUN with normal creatinine (implied by "all labs normal except elevated urea") confirms upper GI source rather than renal dysfunction 1

Important Caveat

• While this presentation is most consistent with PUD, definitive diagnosis requires upper endoscopy with visualization of the ulcer 3
• Dual pathology (bleeding from both upper and lower GI tract) occurs in 1-10% of patients and increases with age, though less likely given the clear upper GI presentation 3
• The absence of NSAID use history or other risk factors in the "normal past medical history" does not exclude PUD, as asymptomatic ulcers commonly present with bleeding 3