Seeking clues for a positive diagnosis of the irritable bowel syndrome

Abstract

Despite its high prevalence the irritable bowel syndrome (IBS) lacks acceptable pathophysiological markers and its diagnosis largely depends on the exclusion of underlying organic disease. Systemic acid-base balance, serum electrolytes and the composition of faecal water (electrolytes and organic anions), were studied in thirty-eight diarrhoeal patients out of a series of ninety-three consecutive IBS patients. Only patients with diarrhoea as the predominant symptom were included in the study to evaluate whether this subgroup could provide the clue for a positive diagnosis of the syndrome. Serum electrolytes and systemic acid-base balance were within the normal range. Faecal electrolytes were also normal (Na 26.6 +/- 19.3 SD; K 66.8 +/- 28.3; Cl 19.1 +/- 15.2 mEq 1(-1)), despite the finding of a moderately increased 24-h faecal output. The K:Na ratio was also within the normal range. These data are in agreement with the lack of systemic changes observed in IBS patients even with profuse or longstanding diarrhoea. Both faecal short chain fatty acids and lactic acid were increased in patients vs. controls, but a considerable overlap with normal values was observed (131.4 +/- 62.6 SD vs. 108.5 +/- 58.3 mEq 1(-1). Only lactic acid concentration was significantly higher than in controls (1.3 +/- 1.2 vs. 0.5 +/- 0.2). Despite these findings it is concluded that the subgroup of IBS patients with diarrhoea also appears to lack a pathophysiological marker and does not provide clues for a positive diagnosis of this syndrome.

Alterations in short-chain fatty acids and serotonin in irritable bowel syndrome: a systematic review and meta-analysis

“…SCFAs, as the main metabolites of the gut microbiota, and 5-HT, as an important regulatory factor of the brain-gut axis, may be involved in the abnormal BGM axis of IBS. Alterations in SCFAs in feces and 5-HT in blood have been found in IBS patients in some studies [27,28,[30][31][32]. This is the first meta-analysis to explore the alterations in SCFAs and 5-HT in IBS, and some interesting findings were observed in our meta-analysis.…”

“…Tana et al [25] found that levels of acetic acid, propionic acid, and total SCFAs were significantly higher in IBS patients than in controls. These findings were [28]. However, Kopecny et al [27] found that the fecal SCFAs of IBS patients were characterized by lower levels of total SCFAs, acetic acid, and propionic acid and by higher levels of butyric acid.…”

“…Similarly, there were no significant differences in acetic acid, propionic acid, or butyric acid between IBS patients and HCs. Although there were no significant alterations in SCFAs in IBS patients, some studies have reported that SCFAs are altered in the feces of IBS patients [25,27,28]. Tana et al [25] found that levels of acetic acid, propionic acid, and total SCFAs were significantly higher in IBS patients than in controls.…”

“…1). Finally, five articles [8,[25][26][27][28] on SCFAs and five articles [29][30][31][32][33] on 5-HT were included in our meta-analysis. The two reviewers from our team were in full agreement in selecting these 10 studies.…”

Diagnostic Procedures in Irritable Bowel Syndrome

“…The colonic exploration as part of the initial work-up of the IBS patient is unclear: authors like Van Der Horst et al [6] believe that a routine contrast enema or colonos copy are unnecessary and that they may increase the anxi ety of the patients, while others, including Schuster [7], advise these examinations to exclude structural abnor malities, in the first place cancer, to reassure the patients and to contribute to a confident therapeutic relationship. Even further going, Vernia et al [8] showed that in patients with suspected IBS and unusual diarrhoea, a clin ical diagnosis of IBS complemented with routine bio chemical testing and examination of the whole colon may not be enough to exclude reliably organic causes of diar rhoea and recommend more extensive investigations in this subgroup of IBS patients.…”