A 47-year-old man comes to the emergency department after an episode of coffee ground emesis. He has had upper abdominal discomfort for several months, which he describes as "burning and fullness" that is relieved by food. Over the last week the patient has had black, tarry stools associated with weakness and fatigue. His medical history is unremarkable. He takes no prescription or over-the-counter medications. The patient smokes a pack of cigarettes a day and occasionally drinks alcohol. His blood pressure is 124/82 mm Hg while supine and 110/70 mm Hg while standing. Pulse is 102/min. On examination, the conjunctivae and palmar creases appear pale. Abdominal examination is unremarkable. Which of the following is most likely increased in this patient?

Question

A 47-year-old man comes to the emergency department after an episode of coffee ground emesis.  He has had upper abdominal discomfort for several months, which he describes as "burning and fullness" that is relieved by food.  Over the last week the patient has had black, tarry stools associated with weakness and fatigue.  His medical history is unremarkable.  He takes no prescription or over-the-counter medications.  The patient smokes a pack of cigarettes a day and occasionally drinks alcohol.  His blood pressure is 124/82 mm Hg while supine and 110/70 mm Hg while standing.  Pulse is 102/min.  On examination, the conjunctivae and palmar creases appear pale.  Abdominal examination is unremarkable.  Which of the following is most likely increased in this patient?

Quizplus · Accepted Answer

This patient has abdominal pain, hematemesis, and melena, likely due to upper gastrointestinal (GI) bleeding from a peptic ulcer. His tachycardia suggests at least mild volume depletion. Patients with upper (but not lower) GI bleeding often have an elevated blood urea nitrogen (BUN) and elevated BUN/creatinine ratio. Possible causes include increased urea production from intestinal breakdown of hemoglobin and increased urea reabsorption in the proximal tubule due to associated hypovolemia. (Choice A) The aldosterone/renin ratio is elevated in primary hyperaldosteronism, in which autonomous secretion of aldosterone suppresses renin release. Patients with acute GI bleeding will usually have proportionate increases in both plasma renin and aldosterone in response to hypovolemia. (Choice B) Alkaline phosphatase is increased in biliary obstruction and skeletal disease with increased osteoblast activity (eg, Paget disease). Mild elevations can be seen in inflammatory bowel disease or intra-abdominal infections. (Choice D) Prolonged prothrombin time can be seen with warfarin use, vitamin K deficiency, certain hereditary coagulation disorders, antibiotic use, and liver disease. (Choice E) The urine sodium (ie, fractional excretion of sodium [FENa]) is often low in patients who are volume depleted as the kidney attempts to retain sodium to restore circulatory volume. Increased FENa is seen in intrinsic renal disease. Educational objective: Patients with upper gastrointestinal bleeding often have an elevated blood urea nitrogen (BUN) and elevated BUN/creatinine ratio, possibly due to increased urea production (from intestinal breakdown of hemoglobin) and increased urea reabsorption (due to hypovolemia). References: Laboratory test variables useful for distinguishing upper from lower gastrointestinal bleeding. (http://www.ncbi.nlm.nih.gov/pubmed/26034359)

A 47-Year-Old Man Comes to the Emergency Department After an Episode