Initial Laboratory Workup for Left Upper Quadrant Pain
For patients presenting with left upper quadrant pain, the initial laboratory workup should include complete blood count (CBC), liver function tests (LFTs), pancreatic enzymes (amylase and lipase), and C-reactive protein (CRP).
Comprehensive Laboratory Panel
Essential Laboratory Tests
Complete Blood Count (CBC)
- Evaluates for leukocytosis, which may indicate infection or inflammation
- Assesses for anemia, which could suggest gastrointestinal bleeding
Liver Function Tests (LFTs)
- Includes transaminases (AST, ALT), alkaline phosphatase, and bilirubin
- Helps identify hepatic pathology or biliary obstruction
Pancreatic Enzymes
- Amylase and lipase to evaluate for pancreatitis
- Particularly important as pancreatitis is a common cause of left upper quadrant pain
Inflammatory Markers
- C-reactive protein (CRP) - values >50 mg/L are suggestive of significant inflammation 1
- Erythrocyte sedimentation rate (ESR) may provide additional information about inflammation
Additional Tests Based on Clinical Suspicion
Urinalysis
- To evaluate for renal pathology or referred pain from urinary tract
Pregnancy test
- For all women of reproductive age 2
- Essential before proceeding with any imaging studies
Diagnostic Approach Based on Laboratory Results
Elevated Pancreatic Enzymes
- If amylase and/or lipase are elevated (typically >3 times upper limit of normal), this strongly suggests acute pancreatitis
- Further imaging with ultrasonography or CT may be indicated
Abnormal Liver Function Tests
- May indicate splenic pathology, left-sided hepatic lesions, or biliary disease
- Elevated transaminases suggest hepatocellular injury
- Elevated alkaline phosphatase and bilirubin suggest biliary obstruction
Leukocytosis with Elevated CRP
- Suggests inflammatory or infectious process
- May indicate conditions such as splenic abscess, diverticulitis extending to left upper quadrant, or perinephric infection
Clinical Pearls and Pitfalls
Common Pitfalls
Overlooking splenic pathology: Splenic infarction, abscess, or torsion can present with left upper quadrant pain and may require specific laboratory and imaging studies 3
Missing pancreatic pathology: Normal amylase levels do not exclude pancreatic injury, especially if measured within 3 hours of symptom onset 1
Relying solely on laboratory tests: Laboratory findings should be interpreted in conjunction with clinical presentation and imaging studies, as normal laboratory values do not exclude significant pathology 1
Important Considerations
Persistently elevated or rising levels of amylase and lipase may have prognostic significance; consider measuring these enzymes every 6 hours in cases of suspected pancreatic injury 1
In patients with suspected diverticulitis extending to the left upper quadrant, CRP >170 mg/L may discriminate severe from mild disease with high sensitivity and specificity 1
Laboratory tests alone are often insufficient for definitive diagnosis of left upper quadrant pain; imaging studies are frequently necessary to establish the diagnosis 4
By following this systematic laboratory workup approach for left upper quadrant pain, clinicians can efficiently narrow the differential diagnosis and determine the need for further imaging studies or specialist consultation.