Following a week of binge drinking, a patient is admitted with severe upper abdominal pain with radiation to the back. He describes the pain as steady, but notes that it is more severe when he lays down on his back. His blood pressure stas to drop, but no source of bleeding is identified. The patient's white count is within normal limits. Which of the following laboratory tests will most likely be diagnostic?

This is a classic presentation of acute pancreatitis. The other classic presentation is as a complication of gallstones occluding the pancreatic duct. Many cases of acute pancreatitis are comparatively mild, but severe cases can cause life-threatening shock secondary to release of vasoactive substances from the damaged pancreas that is difficult to treat. Acute pancreatitis is diagnosed by demonstrating elevated serum amylase levels. Antinuclear antibodies are present in a number of autoimmune diseases, such as systemic lupus erythematosus. IgG levels are not affected by acute pancreatitis. The reticulocyte count is an index of bone marrow function that is used to evaluate the etiologies of some anemias. Ref: Fisher W.E., Anderson D.K., Bell R.H., Saluja A.K., Brunicardi F.C. (2010). Chapter 33. Pancreas. In F.C. Brunicardi, D.K. Andersen, T.R. Billiar, D.L. Dunn, J.G. Hunter, J.B. Matthews, R.E. Pollock (Eds), Schwaz's Principles of Surgery, 9e.