Effects of Thyroid Dysfunction on GI Motility
GI Manifestations of Thyroid Disease
| Hyperthyroidism | Hypothyroidism |
|---|---|
| Upper Gut | Upper Gut |
| Abdominal pain | Dyspepsia |
| Dysphagia | Abdominal pain |
| Atrophic gastritis | Dysphagia |
| Recurrent nausea/vomiting | Achlorhydria |
| H. pylori recurrence | |
| Lower Gut | Lower Gut |
| Lactose intolerance | Small intestinal bacterial overgrowth (SIBO) |
| Diarrhea | Irritable bowel syndrome (IBS) symptoms |
| Colonic pseudo-obstruction | |
| Megacolon | |
| Constipation |
The Relationship Between Thyroid Disorders and GI Motility
Addressing GI Health in Thyroid Disorders
Early intervention for GI health should be integrated into thyroid disease management. For example:
- Probiotic use has been linked to lower TSH levels, reduced thyroid medication doses, and improved fatigue in hypothyroid patients who continue experiencing symptoms despite optimal therapy.
- Treating Helicobacter pylori infections may help reduce the required thyroid hormone replacement dose in affected individuals.
- Dietary modifications can enhance thyroid hormone absorption. A lactose-free diet has been shown to lower TSH levels in individuals with lactose intolerance, which can affect up to 76% of hypothyroid patients. Similarly, adopting a gluten-free diet can reduce thyroid medication needs in those with celiac disease.
- Adequate hydrochloric acid is essential for optimal thyroid hormone absorption, and individuals with hypochlorhydria may require higher doses of thyroid replacement therapy.
Thyroid Hormones Regulate Gut Motility
Thyroid hormones regulate the function of different organs
Thyroid Hormones and Organ Function
Effects of Thyroid Dysfunction on GI Motility
In hyperthyroidism, disruptions in postprandial and basal gastric electrical rhythms have been observed, often leading to delayed gastric emptying at the gastro-duodenal level. Likewise, gastric emptying may also be slowed in hypothyroidism. Individuals with hyperthyroidism commonly experience malabsorption and diarrhea, whereas those with hypothyroidism frequently suffer from constipation and slowed digestive processes
Both hypo- and hyperthyroidism can cause impairment of gastrointestinal motility, modify the structure and function of the pharynx and esophagus, and regulate esophageal peristalsis through neuro-humoral interaction.
In hyperthyroidism, altered postprandial and basic electric rhythms have been observed at the gastro-duodenal level, often resulting in slower gastric emptying. Gastric emptying may also be delayed in hypothyroidism.
Hyperthyroidism is commonly characterized by malabsorption and diarrhea, while hypothyroidism is often characterized by constipation.
GI symptoms linked to thyroid disease
| Hyperthyroidism | Hypothyroidism |
|---|---|
| Upper gut | Upper gut |
| Abdominal pain | Dyspepsia |
| Dysphagia | Abdominal pain |
| Atrophic gastritis | Dysphagia |
| Recurrent nausea/vomiting | Achlorhydria |
| H. pylori recurrence | |
| Lower gut | Lower gut |
| Lactose intolerance | SIBO |
| Diarrhea | IBS features |
| Colonic pseudo-obstruction | |
| Megacolon | |
| Constipation |
Thyroid disorder affects GI motility
Thyroid disorders like hypo- and hyperthyroidism that deregulate its hormonal balance result in imbalances like autoantibody production and bile acid production, thereby leading to GI dysmotility. Impaired GI motility presents itself with features like gastritis, dysphagia, nausea/vomiting, GI bleeding, and SIBO.
Improving GI health should be considered early on in a clinical thyroid workup. For example, probiotic use can help reduce TSH levels, lower thyroid replacement dose, and improve fatigue in hypothyroid subjects with persistent symptoms despite optimum replacement therapy. Treatment for Helicobacter pylori can also reduce thyroid replacement dose in applicable settings.
Addressing food sensitivities and intolerance can improve thyroid replacement absorption. For example, a lactose-free diet was associated with a decrease in TSH levels for those with lactose intolerance, which can affect up to 76% of hypothyroid subjects. Similarly, a gluten-free diet reduced thyroid replacement requirements in subjects with celiac disease.
Hydrochloric acid is required for optimal thyroid replacement absorption and higher doses are needed with hypochlorhydria.
Optimal Takeaways
- Thyroid hormones significantly influence GI motility and function.
- Both hypothyroidism and hyperthyroidism can lead to GI dysmotility, affecting the esophagus, stomach, and intestines.
- Hyperthyroidism is commonly associated with increased motility, diarrhea, and malabsorption, while hypothyroidism often results in constipation and delayed gastric emptying.
- GI symptoms may be the only indication of an underlying thyroid disorder.
- Direct effects on muscle, vagus nerve involvement, and hormonal-metabolic effects may contribute to the effect of thyroid hormones on GI function.
- Addressing GI health can improve thyroid replacement absorption, potentially reducing the dose required to reach a euthyroid state.
- A comprehensive thyroid evaluation should be considered for those with unexplained GI symptoms such as constipation, diarrhea, or motility issues.
Reference
Xu, Guang-Meng et al. “Thyroid disorders and gastrointestinal dysmotility: an old association.” Frontiers in physiology vol. 15 1389113. 2 May. 2024, doi:10.3389/fphys.2024.1389113 This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY).
