Laboratory Workup for Abdominal Pain

Initial Laboratory Evaluation

The American College of Radiology recommends a complete blood count to assess for leukocytosis, which may indicate infection or inflammation in patients with abdominal pain 1
The American Academy of Family Physicians recommends comprehensive metabolic panel including liver function tests for hepatobiliary pathology in patients with abdominal pain 2
Urinalysis is recommended to evaluate for urinary tract infection or nephrolithiasis in patients with abdominal pain 2
Serum lipase is recommended for suspected pancreatitis, as it is more specific than amylase 2
Beta-human chorionic gonadotropin testing is recommended in all women of reproductive age to rule out pregnancy-related conditions including ectopic pregnancy 2, 3

For patients with right upper quadrant pain, liver function tests and hepatobiliary markers are particularly important 2
For patients with right or left lower quadrant pain, a complete blood count with differential is recommended to assess for appendicitis or diverticulitis 1
For patients with diffuse abdominal pain, lactate and D-dimer may be helpful if mesenteric ischemia is suspected 4

In patients with fever and abdominal pain, blood cultures should be considered, especially if sepsis is suspected 1, 5
For immunocompromised patients with abdominal pain, a more extensive workup may be necessary 1, 6
The American Academy of Family Physicians recommends considering elevated cutoff levels for pancreatic enzymes to improve diagnostic accuracy in patients with suspected pancreatitis 2

Failing to obtain pregnancy testing in women of reproductive age before proceeding with imaging studies can lead to delayed diagnosis of pregnancy-related conditions 2, 3
Over-reliance on laboratory tests alone for diagnosis can lead to missed diagnoses, as laboratory findings early in the course of disease may be of little value in differentiating among causes of abdominal pain 1, 4

If initial laboratory workup is inconclusive but clinical suspicion remains high for serious pathology, imaging studies should be considered based on the location of pain 1, 2
For suspected mesenteric ischemia, additional markers such as lactate and D-dimer may be helpful, though they lack specificity 4