An elevation of the leukocyte count favors a surgical cause of abdominal pain, whereas a normal leukocyte count favors a nonsurgical cause. However, the leukocyte count is neither sensitive nor specific enough to confirm appendicitis, even in patients with right lower quadrant pain. Most patients with acute abdominal pain warrant a urinalysis; however, an abnormal urinalysis does not exclude the diagnosis of appendicitis because pyuria and hematuria occur with both appendicitis and urinary tract infection. Physicians often view serum amylase as the gold standard for pancreatitis, ignoring other intra-abdominal conditions that provoke elevations in serum amylase such as biliary tract disease, appendicitis, perforated ulcer, intestinal obstruction, and mesenteric ischemia. The specificity of serum lipase for acute pancreatitis proves invariably higher than serum amylase, especially during the later phases of the disease when lipase levels remain elevated. Thus, the addition of serum amylase testing to serum lipase testing is usually not cost effective.
- A single serum lipase value is a useful screening test for acute pancreatitis because of its high negative predicative value (0.99).
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Seminars in Medical Practice
Hospital Physician Board Review Manuals
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