Relationship Between Hypothyroidism, Risk of Small Intestinal Bacterial Overgrowth, and Duodenal Microbiome Alterations
Authors' conclusion
These findings suggest there is an increased risk for development of SIBO in individuals with a history of hypothyroidism that may be ameliorated by treatment, and may involve specific Gram-negative coliforms.
Study context
- Population
- REIMAGINE study subjects undergoing duodenal aspiration; TriNetX subjects with hypothyroidism or autoimmune thyroiditis
- Exposure
- Hypothyroidism vs controls
- Hypothyroidn = 49
- Controlsn = 323reference
- Outcome
- Incidence and risk of developing SIBO, and changes in small bowel microbial populations
- Follow-up
- 10-year cumulative incidence
Methodological details16S rRNA sequencing, metagenomic sequencing subset, TriNetX Analytics platform
- 16S rRNA sequencing
- Metagenomic sequencing subset
- TriNetX Analytics platform
Main finding
As reported in the abstract
10-year cumulative incidence of SIBO
Relative risk
2.20
HUE vs Matched controls
Relative risk
2.40
Autoimmune thyroiditis vs Matched controls
Observational data: associations, not effects.
Further findings
Small intestinal bacterial overgrowth (SIBO) risk in subjects taking levothyroxine
- HUE taking LT4, RR
- 0.33
- Autoimmune thyroiditis taking LT4, RR
- 0.78
- Risks appeared to be mitigated
Duodenal microbiome
- Genus Neisseria part of the core microbiome in the hypothyroid group but not in nonhypothyroid subjects
- Increased prevalence of Gram-negative coliforms in both SIBO+ groups
- Escherichia/Shigella part of the core in Hypo-/SIBO+; Klebsiella species prevalent in Hypo+/SIBO+
Original publication
Relationship Between Hypothyroidism, Risk of Small Intestinal Bacterial Overgrowth, and Duodenal Microbiome Alterations. J Clin Endocrinol Metab. Published 5 September 2025. doi:10.
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