What laboratory tests should be ordered for a patient presenting with left upper abdominal pain?

Laboratory Tests for Left Upper Abdominal Pain

Ultrasonography of the abdomen is the initial imaging test of choice for patients presenting with left upper abdominal pain, accompanied by appropriate laboratory tests to evaluate potential causes. 1

Initial Laboratory Evaluation

The following laboratory tests should be ordered for patients with left upper abdominal pain:

• Complete Blood Count (CBC) - to assess for infection, inflammation, or blood loss; this is the most frequently ordered test in emergency settings (93% of cases) 2

• Comprehensive Metabolic Panel - to evaluate:

  • Liver function tests (AST, ALT, alkaline phosphatase, bilirubin) - to assess for hepatic disorders 3
  • Electrolytes and renal function (sodium, potassium, BUN, creatinine) - to evaluate for metabolic abnormalities and kidney function 3

• Pancreatic enzymes:

  • Serum lipase - more specific than amylase for pancreatic inflammation, essential for evaluating pancreatitis which can present with left upper quadrant pain 3

• C-reactive protein (CRP) - to assess for inflammation, particularly helpful in cases of suspected diverticulitis, pancreatitis, or other inflammatory conditions 3

• Urinalysis - identified as one of the most useful tests (17% of cases) in the evaluation of abdominal pain 2

• Pregnancy test - for women of childbearing age to rule out ectopic pregnancy or other pregnancy-related complications 3

Condition-Specific Laboratory Tests

Based on the initial clinical assessment, additional tests may be indicated:

• For suspected splenic disorders:

  • Peripheral blood smear - to evaluate for hematologic disorders affecting the spleen 4
  • Coagulation studies (PT/INR, PTT) - if splenic rupture or bleeding is suspected 4

• For suspected gastric disorders:

  • Helicobacter pylori testing - if peptic ulcer disease is suspected 3

• For suspected pancreatic disorders:

  • Serum glucose - to evaluate for complications of pancreatitis 3

Imaging Considerations

While laboratory tests are important, imaging studies are often necessary for definitive diagnosis:

• Ultrasonography is the initial imaging test of choice for left upper quadrant pain, with a rating of 9/9 (usually appropriate) according to ACR Appropriateness Criteria 1

• CT of abdomen with contrast media may be appropriate (rating 6/9) if ultrasonography is inconclusive or if complications are suspected 1

• MRI of abdomen without and with contrast media may be appropriate (rating 6/9) in certain cases, particularly when avoiding radiation exposure is desired 1

Clinical Correlation

Laboratory findings should always be interpreted in the context of the patient's clinical presentation:

• Leukocytosis (elevated WBC count) may indicate infection or inflammation but lacks specificity to distinguish between bacterial and viral infections 5

• Normal laboratory values do not exclude serious pathology - up to 25% of patients with acute mesenteric ischemia, which can present with left upper quadrant pain, may have normal initial laboratory tests 1

Common Pitfalls to Avoid

• Relying solely on laboratory tests without appropriate imaging - many conditions causing left upper quadrant pain require imaging for definitive diagnosis 1

• Overlooking extra-abdominal causes of pain - respiratory infections and other non-abdominal conditions can present with referred abdominal pain 3

• Failing to repeat laboratory tests when clinical suspicion remains high despite initial negative results - some conditions may show laboratory abnormalities only as they progress 1

• Assuming normal WBC count excludes serious pathology - the WBC count lacks sensitivity in some patients and may not reliably correlate with disease severity 5

By following this structured approach to laboratory testing, clinicians can efficiently evaluate patients with left upper abdominal pain while minimizing unnecessary testing and avoiding diagnostic delays.