Keywords
constipation
Hashimoto’s thyroiditis
hypothyroidism
gut microbiome
small intestinal bacterial overgrowth
How to Cite
Abstract
Abstract. Irritable bowel syndrome (IBS) is common gastrointestinal disorder. Gut microbiome composition changes play a significant role in its pathogenesis. Hashimoto’s thyroiditis (HT) often coexists with IBS and may worsen its clinical course. Small intestinal bacterial overgrowth (SIBO) is highly prevalent in both diseases.
The aim of study was to determine the gut microbiome composition and SIBO frequency in patients with IBS with constipation (IBS-C) and hypothyroid HT.
Material and methods. This pilot single-center, cross-sectional study included 25 patients with IBS-C. Based on hypothyroid HT status they were divided into 2 groups: 18 patients with IBS-C and HT with hypothyroidism (study group) and 7 patients with IBS-C (control group). Determination of microbiota composition (Lactobacillus spp., Bifidobacterium spp., Escherichia coli, Bacteroides fragilis group, Bacteroides tetaitaomicron, Fecalibactrerium prausnitzii, Enterococcus spp., Roseburia inulinivorans) was performed with quantitative real-time polymerase chain reaction. Glucose hydrogen breath test was used to diagnose SIBO. Statistical analyses were performed using R version 4.4.1 and EZR version 1.68.
Results. A trend for higher total bacterial count was observed in IBS-C patients with hypothyroid HT. Firmicutes/Bacteroidetes ratio was significantly lower (p=0.031) and Bacteroides fragilis group / Faecalibacterium prausnitzii ratio was significantly higher (p=0.001) in patients of study group compared to control group. In study group patients amounts of Lactobacillus spp., Bifidobacterium spp. and Escherichia coli were significantly lower, while levels of Bacteroides fragilis group and Roseburia inulinivorans were higher (p<0,05). SIBO frequency in hypothyroid
HT patients with IBS-C was high (61.1%). Study group also was characterized by significantly higher absolute rise in breath hydrogen above baseline levels compared to control group.
Conclusions. IBS-С patients with coexisting hypothyroid HT demonstrated significant gut microbiota alterations, such as lower Firmicutes/Bacteroidetes ratio and higher Bacteroides fragilis group / Faecalibacterium prausnitzii ratio, the high rate of SIBO-positive cases and higher frequency of SIBO and a more intense increase in the hydrogen content in the air during a breath test.
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