If you’re preparing for the United States Medical Licensing Examination® (USMLE®) Step 2 exam, you might want to know which questions are most often missed by test-prep takers. Check out this example from Kaplan Medical, and read an expert explanation of the answer. Also check out all posts in this series.
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This month’s stumper
A 39-year-old man comes to the emergency department because of a two-day history of severe epigastric pain that radiates to the back, nausea, and vomiting. He reports that he had three similar episodes during the past year that required hospitalization. He drinks 16 to 20 beers daily. He has smoked two packs of cigarettes daily for 20 years. His temperature is 38.4ordmC (101ordmF), blood pressure is 114/70 mm Hg, and pulse is 110 per minute. Laboratory studies show hemoglobin is 12.4 g/dL.
Serum studies show:
- Na+ 141 mEg/L.
- CI 90 mEg/L.
- K+ 3.7 mEg/L.
- HCO- 39 mEg/L.
- Urea nitrogen (BUN) 25 mg/dL.
- Creatinine 1.1 mg/dL.
- Amylase 300 U/L.
- Lipase 275 U/L.
Which of the following complications is most likely in this patient?
A. Alveolar capillary membrane destruction due to circulating phospholipase.
B. Development of a carcinoma as a result of pancreatic duct injury.
C. Hypercalcemia as a result of stimulation of parathyroid secretion.
D. Hypertension due to altered intravascular volume.
E. Hypoglycemia due to impaired insulin production.
The correct answer is A.
Kaplan Medical explains why
Acute pancreatitis is suggested by this patient's severe epigastric pain, which radiates to his back and is accompanied by nausea and vomiting. The diagnosis is confirmed by demonstrating serum elevation of the pancreatic enzymes amylase and lipase. More than 80% of the hospital admissions for acute pancreatitis are related to either biliary tract disease (typically with a stone lodging in the duct system below the entry of the pancreatic duct) or alcoholism, and this patient admits to recent active drinking.
Acute pancreatitis is a very dangerous disease, not only because it potentially destroys large areas of pancreatic tissue, but also because the destruction of the exocrine gland tissues potentially releases a great many enzymatically or physiologically active substances into the bloodstream. Among the released substances is phospholipase, which circulates through the bloodstream and damages the alveolar capillary membranes in the lungs, predisposing for adult respiratory distress syndrome.
Why the other answers are wrong
Choice B: Pancreatic cancer does not develop as a sequela of acute pancreatitis.
Choice C: Hypercalcemia does not occur as a result of pancreatitis, although it may be an infrequent cause of pancreatitis. Hypocalcemia occurs in severe pancreatitis by saponification of calcium by free fatty acids and undigested fats.
Choice D: Decreased intravascular volume does occur, but it leads to hypotension, not hypertension.
Choice E: In patients who have severe pancreatitis, insulin production and release is impaired, leading to hyperglycemia rather than hypoglycemia.
Tips to remember
- Acute pancreatitis presents with severe epigastric pain that radiates to the back, along with nausea and vomiting; symptoms are generally worse with eating.
- Acute pancreatitis is characterized by the release of pancreatic enzymes, which cause inflammation through digesting body tissues.
- Acute respiratory distress syndrome is a life-threatening complication of acute pancreatitis caused by release of phospholipase, which circulates through the bloodstream and damages the alveolar capillary membranes in the lungs.
For more prep questions on USMLE Steps 1, 2 and 3, view other posts in this series.