Although many experts recommend a 72-hour stool collection for fat and weight, this is often unnecessary and impractical in both outpatient and hospital settings. Patients should maintain a regular diet, trying to consume at least 100 g of fat daily. The two most common causes of steatorrhea in the United States are celiac sprue and pancreatic insufficiency, which is usually a result of chronic pancreatitis. When pancreatic insufficiency appears likely, as in cases of chronic alcoholism, a trial of pancreatic enzymes is often reasonable before extensive diagnostic tests are performed. Pancreatic cancer is an uncommon cause of steatorrhea.
Celiac sprue is the most common small intestinal mucosal disease in the United States.
The key to diagnosis is small bowel biopsy, which is done most often by means of upper GI endoscopy. Irritable bowel syndrome is probably the most common cause of diarrhea in the United States. The disorder is thought to be functional in that no organic abnormality of the GI tract can be detected. Typical symptoms include diarrhea that is often watery, usually alternating with constipation, along with bloating and abdominal discomfort. A reasonable evaluation should include history, physical examination, complete blood count, and Hemoccult testing.