Correspondence
Patients with Chronic Diarrhea
N Engl J Med 1995; 333:257-258July 27, 1995
- Article
To the Editor:
In the review article by Donowitz et al. (March 16 issue),1 there is no mention of measuring serum or red-cell folate, serum B12, or autoantibodies in the evaluation of patients with chronic diarrhea. These tests are readily available and inexpensive, and the presence of a low concentration of red-cell folate or antiendomysial or antireticulin antibodies would alert the investigator to the possibility of celiac disease at an early stage. Folate deficiency is almost invariably present in patients with untreated celiac disease, and antiendomysial antibodies are present in 90 to 100 percent of them.2,3 Furthermore, the concentrations of red-cell folate and serum B12 are often abnormal in patients with Crohn's disease and are useful indicators of the need for subsequent investigation of the small bowel. In the stepwise approach suggested by the authors, a small-bowel biopsy is performed as a second-stage investigation. Thus, patients with celiac disease would already have undergone thyroid-function testing, serum gastrin measurement, and plain abdominal radiographic and barium studies of the upper gastrointestinal tract, small bowel, and colon before the correct diagnosis was made.
3 ReferencesAnne B. Ballinger, M.R.C.P.
Ana Maria Cevallos, M.D.
Michael L. Clark, M.D.
Medical College of St. Bartholomew's Hospital, London EC1M 6BQ, United Kingdom1
Donowitz M ,Kokke FT ,Saidi R . Evaluation of patients with chronic diarrhea. N Engl J Med 1995;332:725-729
Full Text | Web of Science | Medline2
Ferreira M ,Davies SL ,Butler M ,Scott D ,Clark M ,Kumar P . Endomysial antibody: is it the best screening test for coeliac disease? Gut 1992;33:1633-1637
CrossRef | Web of Science | Medline3
Ladinser B ,Rossipal E ,Pittschieler K . Endomysium antibodies in coeliac disease: an improved method. Gut 1994;35:776-778
CrossRef | Web of Science | Medline
To the Editor:
In their review article on chronic diarrhea, Donowitz et al. suggest a two-stage evaluation of outpatients. In stage 1 they propose stool, blood, radiologic, and endoscopic studies. They do not include ultrasonography with high-frequency probes (5 and 7 MHz). This inexpensive, noninvasive procedure yields additional information useful in the diagnosis of chronic diarrhea: the thickness of the bowel (which allows one to distinguish between functional and organic disease such as Crohn's disease, lymphoma, and cancer), the size of lymph nodes (for the diagnosis of lymphoma and AIDS), and the structure of the pancreas (for the diagnosis of cancer and chronic pancreatitis).
Mario Cottone, M.D.
Rita Aiala, M.D.
Roberto Di Mitri, M.D.
Ospedale V. Cervello, 90146 Palermo, ItalyTo the Editor:
Donowitz et al. provided us with a logical sequential approach to the evaluation of patients with chronic diarrhea. Although it is all too easy to quibble over some of the particulars, I would question the categorization of the enzyme-linked immunosorbent assay for giardia antigen as a stage 2 test, to be performed only after barium studies of the upper and lower gastrointestinal tract, sigmoidoscopy, and biopsy. Indeed, in the text it does appear to be considered more as a screening assay than as one of the “more invasive and costly” stage 2 tests. Suggestions for additional tests to add to the schemata include an assay for alpha1-antitrypsin in the stool as a noninvasive method of diagnosing protein-losing enteropathy,1 and a celiac antibody panel. The latter would seem well advised, considering the difficulty (which the authors concede) of interpreting fecal-fat studies, their primary means of screening for malabsorption in the stage 1 evaluation.
1 ReferencesLarry Eisenberg, M.D.
18372 Clark St., Tarzana, CA 913561
Crossley JR ,Elliott RB . Simple method for diagnosing protein-losing enteropathies. BMJ 1977;1:428-429
CrossRef | Web of Science | Medline
Author/Editor Response
The authors reply:
To the Editor: Some of the letters question placing a test in the first rather than the second stage of the evaluation of chronic diarrhea. Our basis for placing a test in the first rather than the second stage was that it was cheaper and easier to do than other tests, was more convenient for the patients, or was likely to save money. Dr. Eisenberg suggests performing an enzyme-linked immunosorbent assay of the stool for giardia antigen in the first stage of the evaluation. We agree that this is a highly specific, very sensitive, and relatively inexpensive test. However, examination of stools for ova and parasites is being performed for multiple parasites, and we feel that we should obtain the results of the initial tests for ova and parasites before we do additional ones for giardia.
Dr. Eisenberg and Ballinger et al. suggest performing serum antibody assays as an early screening method for patients with chronic diarrhea due to celiac sprue. Despite their high sensitivity and specificity (particularly of the antiendomysial antibody), we do not favor the use of these screening tests since, if abnormal, they would lead us to do a small-intestinal biopsy, which is already part of our stage 2 evaluation. That is, a positive test would not cause us to do anything differently in stage 2. Similarly, using a screening test to detect protein-losing enteropathy, which is not a specific cause of chronic diarrhea but rather results from one of the causes already being considered, will not change the basic evaluation we are proposing. Ballinger et al. speculate on the number of tests that an antibody test suggestive of celiac sprue would prevent. We think it would be of interest to know how often physicians of patients in whom celiac sprue is newly diagnosed fail to have thyroid-function tests and radiographic studies of the upper gastrointestinal tract, small bowel, and colon performed after the diagnosis. We suspect most would order these tests.
Cottone et al. speculate on the use of endoscopic ultrasonography of the rectum early in the evaluation of chronic diarrhea. Certainly, a prospective study to evaluate how frequently this procedure would prevent some or all of the need for stage 2 evaluations would be worth doing, but we know of no study that has addressed this issue yet.
Mark Donowitz, M.D.
Freddie Kokke, M.D.
Roxan Saidi, M.D.
Johns Hopkins University School of Medicine, Baltimore, MD 21205
