Guidelines for the investigation of chronic diarrhoea, 2nd edition

Pre-endoscopy serological testing for coeliac disease: evaluation of a clinical decision tool

OBJECTIVE

To determine an effective diagnostic method of detecting all cases of coeliac disease in patients referred for gastroscopy without performing routine duodenal biopsy.

DESIGN

An initial retrospective cohort of patients attending for gastroscopy was analysed to derive a clinical decision tool that could increase the detection of coeliac disease without performing routine duodenal biopsy. The tool incorporated serology (measuring antibodies to tissue transglutaminase) and stratifying patients according to their referral symptoms (patients were classified as having a "high risk" or "low risk" of coeliac disease). The decision tool was then tested on a second cohort of patients attending for gastroscopy. In the second cohort all patients had a routine duodenal biopsy and serology performed.

SETTING

Teaching hospital in Sheffield.

PARTICIPANTS

2000 consecutive adult patients referred for gastroscopy recruited prospectively.

MAIN OUTCOME MEASURE

Evaluation of a clinical decision tool using patients' referral symptoms, tissue transglutaminase antibody results, and duodenal biopsy results.

RESULTS

No cases of coeliac disease were missed by the pre-endoscopy testing algorithm. The prevalence of coeliac disease in patients attending for endoscopy was 3.9% (77/2000, 95% confidence interval 3.1% to 4.8%). The prevalence in the high risk and low risk groups was 9.6% (71/739, 7.7% to 12.0%) and 0.5% (6/1261, 0.2% to 1.0%). The prevalence of coeliac disease in patients who were negative for tissue transglutaminase antibody was 0.4% (7/2000). The sensitivity, specificity, positive predictive value, and negative predictive value for a positive antibody result to diagnose coeliac disease was 90.9%, 90.9%, 28.6%, and 99.6%, respectively. Evaluation of the clinical decision tool gave a sensitivity, specificity, positive predictive value, and negative predictive value of 100%, 60.8%, 9.3%, and 100%, respectively.

CONCLUSIONS

Pre-endoscopy serological testing in combination with biopsy of high risk cases detected all cases of coeliac disease. The use of this decision tool may enable the endoscopist to target patients who need a duodenal biopsy.

Best practice in primary care pathology: review 6

This sixth best practice review examines four series of common primary care questions in laboratory medicine: (1) laboratory monitoring in hypertension and heart failure abnormalities; (2) markers of inflammatory joint disease; (3) laboratory investigation of chronic diarrhoea; and (4) mumps and chickenpox. The review is presented in question-answer format, referenced for each question series. The recommendations represent a precis of guidance found using a standardised literature search of national and international guidance notes, consensus statements, health policy documents and evidence-based medicine reviews, supplemented by Medline Embase searches to identify relevant primary research documents. They are not standards but form a guide to be set in the clinical context. Most are consensus based rather than evidence based. They will be updated periodically to take account of new information.

Is exocrine pancreatic insufficiency in adult coeliac disease a cause of persisting symptoms?

BACKGROUND

Patients with coeliac disease may have diarrhoea despite being on a gluten-free diet.

AIM

To assess whether exocrine pancreatic insufficiency causes persisting symptoms compared with controls, we determined whether pancreatic enzyme supplementation provided symptomatic benefit in coeliac patients with chronic diarrhoea.

METHODS

Patients (n = 259) were subdivided into four groups: (a) new coeliac disease (n = 57), (b) coeliac disease patients on a gluten-free diet without gastrointestinal symptoms (n = 86), (c) coeliac disease patients on a gluten-free diet with chronic diarrhoea (n = 66) and (d) patients with chronic diarrhoea without coeliac disease (n = 50). Stool frequency and weight, before and after treatment with pancreatic enzyme supplementation were recorded.

RESULTS

The prevalence of a low faecal elastase-1 within the groups was: group (A) six of 57 (11%), group (B) five of 86 (6%), group (C) 20 of 66 (30%) and group (D) two of 50 (4%). Low faecal elastase-1 was more frequent in coeliac disease patients with chronic diarrhoea vs. other subgroups of coeliac disease (P < or = 0.0001) and controls (P < or = 0.0003). In 18 of 20 stool frequency reduced following pancreatic enzyme supplementation from four per day to one (P < or = 0.001). No weight increase (P = 0.3) was observed.

CONCLUSIONS

Low faecal elastase is common in patients with coeliac disease and chronic diarrhoea, suggesting exocrine pancreatic insufficiency. In this group of patients, pancreatic enzyme supplementation may provide symptomatic benefit.

Differential diagnosis between functional and organic intestinal disorders: Is there a role for non-invasive tests?

Abdominal pain and bowel habits alterations are common symptoms in the general population. The investigation to differentiate organic from functional bowel disorders represents a considerable burden both for patients and public health service. The selection of patients who should undergo endoscopic and/or radiological procedures is one of the key points of the diagnostic process, which should avoid the abuse of invasive and expensive tests as well as the underestimation of potentially harmful diseases. Over the coming years, clinicians and researchers will be challenged to develop strategies to increase the patient’s compliance and to reduce the economic and social costs of the intestinal diseases.

Factitious Diarrhea Induced by Stimulant Laxatives: Accuracy of Diagnosis by a Clinical Reference Laboratory Using Thin Layer Chromatography

Background: Surreptitious ingestion of laxatives can lead to serious factitious diseases that are difficult to diagnose. Most cases involve ingestion of bisacodyl or senna. Thin layer chromatography (TLC) of urine or stool is the only commercially available test for these laxatives. Such testing is considered highly reliable, but its accuracy in clinical practice is unknown. Our aim was to evaluate the reliability of TLC laxative testing by a clinical reference laboratory in the United States.

Methods: Diarrhea was induced in healthy volunteers by ingestion of bisacodyl, senna, or a control laxative (n = 11 for each laxative group). Samples of urine and diarrheal stool were sent in blinded fashion to the clinical reference laboratory for bisacodyl and senna analysis.

Results: TLC testing for bisacodyl-induced diarrhea revealed a sensitivity of 73% and specificity of 91% when urine was tested and sensitivity and specificity of 91% and 96%, respectively, when stool was analyzed. When diarrhea was induced by senna, the TLC assay for senna failed to identify even a single urine or stool specimen as positive (zero% sensitivity).

Conclusions: Considering the expected prevalence of surreptitious laxative abuse in patients with chronic idiopathic diarrhea (2.4%–25%, depending on the clinical setting), TLC of urine or stool for bisacodyl by this reference laboratory would often produce misleading results, and testing for senna would have no clinical value. The major problems are false-positive tests for bisacodyl and false-negative tests for senna.

Usefulness of duodenal biopsy during routine upper gastrointestinal endoscopy for diagnosis of celiac disease

AIM: To describe the trend in duodenal biopsy performance during routine upper gastrointestinal endoscopy in an adult Spanish population, and to analyze its value for the diagnosis of celiac disease in clinical practice.

METHODS: A 15 year-trend (1990 to 2004) in duo-denal biopsy performed when undertaking upper gastrointestinal endoscopy was studied. We analysed the prevalence of celiac disease in the overall group, and in the subgroups with anaemia and/or chronic diarrhoea.

RESULTS: Duodenal biopsy was performed in 1033 of 13 678 upper gastrointestinal endoscopies (7.6%); an increase in the use of such was observed over the study period (1.9% in 1990-1994, 5% in 1995-1999 and 12.8% in 2000-2004). Celiac disease was diagnosed in 22 patients (2.2%), this being more frequent in women than in men (3% and 1% respectively). Fourteen out of 514 (2.7%) patients with anaemia, 12 out of 141 (8.5%) with chronic diarrhoea and 8 out of 42 (19%) with anaemia plus chronic diarrhoea had celiac disease. A classical clinical presentation was observed in 55% of the cases, 23% of the patients had associated dermatitis herpetiformis and 64% presented anaemia; 9% were diagnosed by familial screening and 5% by cryptogenetic hypertransaminasaemia.

CONCLUSION: Duodenal biopsy undertaken during routine upper gastrointestinal endoscopy in adults, has been gradually incorporated into clinical practice, and is a useful tool for the diagnosis of celiac disease in high risk groups such as those with anaemia and/or chronic diarrhoea.

Symptom management of HIV-related diarrhea by using normal foods: A randomized controlled clinical trial

The purpose of this randomized clinical trial was to determine the efficacy of a dietary intervention to reduce the frequency of bowel movements and improve stool consistency as compared with subjects assigned to a control group. The study enrolled HIV patients with a history of three or more episodes of diarrhea for 3 weeks or more. Seventy-five subjects were enrolled, of which 38 were randomized to the treatment group and 37 to the control group. Six study sessions were scheduled over a 24-week period. At 24 weeks, the stool frequency reduced 28% in the treatment group and 15% in the control group (F = 9.22, p < .001) and stool consistency improved 20% in the treatment group and 8% in the control group (F = 9.98, p < .001). The results showed that the intervention was effective in reducing stool frequency and improving stool consistency in HIV patients with chronic diarrhea for up to 6 months of treatment.

Measurement of faecal fat excretion: an evaluation of attitudes and practices of Australian gastroenterologists

BACKGROUND

Although faecal fat excretion over 72 h is the gold standard for quantifying fat malabsorption, there has been a push from chemical pathology laboratories to discontinue this test, arguing that it is unreliable and of limited clinical value.

AIMS

To assess attitudes, knowledge and practices of Australian gastroenterologists in relation to the test and to gauge opinion as to whether it should remain available.

METHODS

A self-administered questionnaire was developed to assess attitudes towards, patterns of use and understanding of 72-h faecal fat collections. This was posted to all members of the Gastroenterological Society of Australia.

RESULTS

Of 429 eligible gastroenterologists, 124 (29%) responded. Eighty-two per cent utilized the test; 62% at least once per year. Main indications were suspected steatorrhoea (55%), unexplained chronic diarrhoea (39%) or weight loss (29%). Thirty-eight per cent ordered the test to determine stool volume. Only 26% attempted to appropriately fat load patients and approximately half did not recognize the potential influence of medications and stool volume. This was also reflected in poor interpretation of results in specific clinical scenarios. Of those who use the test at least once per year, 97% wanted its continued availability and 51% felt their practice would be significantly affected if the test was discontinued.

CONCLUSIONS

Although continued availability of 72-h faecal fat estimation is supported by many Australian gastroenterologists, the test appears to be often performed and interpreted suboptimally. Rather than discard the test, efforts should more appropriately be directed to improving baseline knowledge to ensure its optimal performance and interpretation.

Systematic review: microscopic colitis

BACKGROUND

Collagenous and lymphocytic colitis are fairly common causes of chronic non-bloody diarrhoea, especially in elderly female.

AIM

To present a systematic review of microscopic colitis.

METHODS

A PubMed search using the MeSH terms microscopic colitis, collagenous colitis, lymphocytic colitis and chronic diarrhoea was performed.

RESULTS

Annual incidence of each disorder is 4-6/100,000 inhabitants. The aetiology is unknown. Clinical characteristics are well described and there is an association with autoimmune diseases. Budesonide is the best-documented short-term treatment of collagenous colitis. In meta-analysis pooled odds ratio for clinical response after 6-8 weeks of treatment was 12.3 (95% CI: 5.5-27.5) in comparison with placebo. The evidence for bismuth subsalicylate is weaker and the effectiveness of other alternatives such as loperamide, cholestyramine, aminosalicylates, probiotics, or Boswellia serrata extract is unknown. Although unproven, in unresponsive severe disease azathioprine or methotrexate may be tried. No controlled trials have been carried out in lymphocytic colitis. The long-term prognosis of microscopic colitis is good, serious complications are rare and there is no increased mortality.

CONCLUSIONS

Clinical and epidemiological aspects of microscopic colitis are well described. Budesonide is the best-documented short-term therapy in collagenous colitis, but the optimal long-term strategy needs further study. Controlled treatment data of lymphocytic colitis are awaited for.

Routine ileoscopy at colonoscopy: a prospective evaluation of learning curve and skill-keeping line

BACKGROUND

Ileoscopy is the criterion standard for mucosal lesions of terminal ileum but is performed in 5% of colonoscopy activity, and the need for training is undefined.

OBJECTIVE

To assess the learning curve and skill-keeping line of ileoscopy.

DESIGN

Prospective randomized study.

SETTING

Single GI endoscopy unit.

PATIENTS

Adult outpatients referred for colonoscopy.

INTERVENTIONS

Patient randomization to ileocolonoscopy by trainees and seniors.

MAIN OUTCOME MEASUREMENTS

Ileoscopy skill was divided into the following: ileocecal valve (ICV) intubation (success rate, time) and ileal exploration (length, time). Consecutive blocks of 10 procedures were used to calculate the learning curve and the skill-keeping line. Variables considered to influence ICV intubation were the following: endoscopist experience, ICV morphology, patient age, gender, body mass index, diverticular disease, and preceding abdominal/pelvic surgery.

RESULTS

Learning curve showed that competency in ICV intubation (80% success rate) and ileal exploration (16 cm) was achieved after 50 procedures. The skill-keeping line showed that ileoscopy was easy (97% success rate), fast (1 minute), and well accepted up to 45 cm of the ileum. Thin-lipped and volcanic ICV are the most difficult and easiest to intubate, respectively. Crohn's disease and adenomas of the proximal edge of ICV were diagnosed in 2.2%.

CONCLUSIONS

Training in ileoscopy is recommended to achieve competency, and endoscopists should consider practicing ICV intubation to maintain and increase their skill. Ileoscopy can be difficult when the ICV is thin lipped or single bulged, and easy when it has a volcanic morphology.

Small Bowel Bacterial Overgrowth in Symptomatic Older People: Can It Be Diagnosed Earlier?

BACKGROUND/OBJECTIVES

In older people, small bowel bacterial overgrowth syndrome may be a common, but under-diagnosed, cause of diarrhoea and nutrient malabsorption. We aim to determine which clinical features and baseline laboratory investigations indicate a high likelihood of small bowel bacterial overgrowth as defined by a positive glucose breath test.

METHODS

A retrospective analysis of records for all patients referred for glucose breath test over a 6-year period to a teaching hospital.

RESULTS

Out of 197 referrals, 168 patient records were located and analysed (62 male, 106 female; median age 65). Patient characteristics predictive of a positive glucose breath test were: increasing age (p < 0.01), low serum vitamin B12 (p = 0.02), low serum albumin (p = 0.03), previous partial gastrectomy (p < 0.01), previous right hemi-colectomy (p < 0.01), presence of small bowel diverticulae (p = 0.01) and concurrent use of a proton pump inhibitor (p < 0.01). 52.5% (n = 21/40) of patients studied who were over 75 years old versus 21.8% (n = 28/128) of those under 75 years old had a positive glucose breath test (p < 0.01). The median time to diagnosis, from first hospital visit to positive glucose breath test, was 39 weeks.

CONCLUSIONS

There is often a significant delay in diagnosis of small bowel bacterial overgrowth. We suggest that this diagnosis should be considered earlier in the investigative algorithm in older patients with indicative symptoms and a predisposing factor (including previous partial gastrectomy, previous right hemi-colectomy, small bowel diverticulae or use of a proton pump inhibitor) or concurring laboratory indices (low vitamin B12 or albumin).

Routine isotope-dilution liquid chromatography-tandem mass spectrometry assay for simultaneous measurement of the 25-hydroxy metabolites of vitamins D2 and D3

BACKGROUND

Measurement of 25-hydroxyvitamin D2 and D3 (25-OH D2 and D3) is essential for investigating vitamin D deficiency. Competitive binding techniques are unable to distinguish between the 2 metabolites and suffer from interference from other hydroxy metabolites of vitamin D.

METHODS

We used isotope-dilution liquid chromatography-tandem mass spectrometry (ID-LC-MS/MS) for routine determination of 25-OH D2 and D3 with a stable-isotope-labeled internal standard (IS). Serum samples (100 microL) were denatured with methanol-propanol containing IS, vortex-mixed, extracted into hexane, and dried under nitrogen. The reconstituted extract was chromatographed on a BDS C8 HPLC column, and the metabolites and IS were detected by electrospray ionization MS/MS in multiple-reaction monitoring mode.

RESULTS

25-OH D2 and D3 and the IS nearly coeluted, whereas 1alpha-hydroxyvitamin D3 was separated; total run time was 8 min. The interassay CVs for 25-OH D2 were 9.5% and 8.4% at 52 and 76 nmol/L, respectively, and for 25-OH D3 were 5.1% and 5.6% at 55 and 87 nmol/L, respectively. The detection limit of the present method was <4 nmol/L for both metabolites. Method comparison with a commercial RIA measuring total 25-hydroxyvitamin D showed good correlation: y=0.97x - 2.7 nmol/L (r=0.91). The analytical system can assay 100 samples in 12.5 h.

CONCLUSIONS

This simple robust interference-free LC-MS/MS assay is suitable for routine measurement of the 25-hydroxy metabolites of vitamins D2 and D3 in human serum. The assay has been in use for 9 months and has been used to assay more than 6000 routine samples.