CAT scan to evaluate weight loss

The leading causes of involuntary weight loss are depression, cancer (lung and gastrointestinal malignancies), cardiac disorders and benign gastrointestinal diseases. Medications that may cause nausea and vomiting, dysphagia, dysgeusia and anorexia have been implicated. Polypharmacy can cause unintended weight loss, as can psychotropic medication reduction (i.e., by unmasking problems such as anxiety). A specific cause is not identified in approximately one quarter of patients with unintentional weight loss. A reasonable work-up includes tests dictated by the history and physical examination, a fecal occult blood test, a complete blood count, a chemistry panel, an ultrasensitive thyroid-stimulating hormone test and a urinalysis. Upper gastrointestinal studies have a reasonably high yield in selected patients.

Some diagnostic modalities, such as computed tomographic (CT) scanning, have particularly low yields. In one series, CT scanning provided no new information beyond confirming one cancer that was already suspected. In the same series, diagnostic yields (positive tests) were highest for fecal occult blood testing (18 percent), sigmoidoscopy (18 percent), thyroid function testing for both hyperthyroidism and hypothyroidism (24 percent), upper endoscopy (40 percent) and upper gastrointestinal series (44 percent).

Thompson MP, Morris LK. Unexplained weight loss in the ambulatory elderly. J Am Geriatr Soc 1991; 39:497-500.

New York State Department of Health. General nutrition, weight loss, and wasting syndrome. New York (NY): New York State Department of Health; 2004 Mar. 21 p. [35 references]
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