A 77-year-old woman is brought to the emergency room because of symptoms of nonspecific abdominal discomfort. She has no anorexia, fever, chills, or weight loss. On physical examination, the vital signs are normal, the abdomen is soft and nontender with no masses or organomegaly palpated. Abdominal x-rays show lots of stool in the colon, but no free air or air- fluid levels. Laboratory investigations reveal an amylase of 150 U/L (25-125 U/L), and the rest of her biochemistry and complete blood count are normal. Which of the following conditions can cause a false-positive elevation in the serum amylase?
High-Yield Explanation
Amylase accumulates in the setting of renal failure, and thus becomes a less-valuable diagnostic test (false positive). Numerous other conditions involving the pancreas, the gut, and the salivary glands can raise amylase levels. Sulfonamides cause pancreatitis; therefore, an elevated amylase is not confusing, but rather a useful test for pancreatitis in patients taking the drug. Morphine can elevate amylase levels in the absence of pancreatitis.