A 49-year-old man with alcohol use disorder is evaluated in the emergency department for a 36-hour history of nausea and vomiting associated with severe abdominal pain radiating to his back.
Temperature is 38.4 °C (101.2 °F), blood pressure is 150/90 mm Hg, and pulse rate is 110/min. The abdomen is distended, and epigastric tenderness to palpation is present.
Which of the following is the best predictor of severe disease in this patient?