Decreased expression of ileal thyroid hormone transporters in a hypothyroid patient: a case report
Open accessAbstract
Background: Malabsorption of levothyroxine (LT4) is a common problem faced in clinical practice. It is usually solved, if there are no complexities including gastrointestinal absorption disorder, by taking medicines on an empty stomach and avoiding foods interfering with LT4. Herein we present a rare case of a patient exhibiting malabsorption of LT4 with decreased membranous expression of ileal transporters. Case: The 22-Year-old female presented with sustained hypothyroid status despite medication of 7.8 μg/kg LT4. Medical history and LT4 absorption test (the absorption rate 8.4%) excluded pseudomalabsorption. No organic gastrointestinal disorder was found in the patient by blood chemistry, endoscopies, and abdominal computed tomography scan. The immunohistochemical analysis showed decreased membranous expression of LAT1 and LAT2 in distal ileum and ascending colon in the patient compared to 20 controls who have no thyroid disease. The expression of MCT8 in colon appeared at both nucleus and brush border in the patient, while it was limited to brush border in controls. The expression of other transporters was similar between the patient and controls. Conclusion: The changes of the expression of LAT1 and LAT2 in this patient showing LT4 malabsorption might help to understand the role of intestinal transporters in the absorption of LT4 in humans. The functional relevance of the decrement of LAT1 and LAT2 in this patient remains to be elucidated.
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These transporters are responsible for both the influx and the efflux of T4.
“These transporters are responsible for both the influx and the efflux of T4.”
From Levothyroxine: conventional and novel drug delivery formulations. (2023) · cites this paper as [27]
The expression of these LT4 transporters is not limited to enterocytes, as their expression is also detected in peripheral organs.
“The expression of these transporters is not limited to enterocytes, as their expression is also detected in peripheral organs.”
From Levothyroxine: conventional and novel drug delivery formulations. (2023) · cites this paper as [27]
The full mechanism by which levothyroxine crosses the intestinal mucosa is not known, but it appears to involve transmembrane proteins such as organic anion transporters, Na-taurocholate cotransporter, L-type amino acid transporters 1 and 2, and monocarboxylate transporters 8 and 10.
“The complete mechanism of LT4 transport across the intestinal mucosa is not fully understood, but it appears to involve the participation of transmembrane proteins, such as the organic anion transporters family, Na-taurocholate cotransporter, amino acid transporters type L 1 and 2, and monocarboxylate transporters 8 and 10, which are responsible for the entry and exit of thyroxine (T4).20”
From Refractory hypothyroidism: unraveling the complexities of diagnosis and management (2023) · cites this paper as [20]
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Optimal thyroid hormone replacement
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- Authors
- Chung, C. W., Mo, E. Y., Jung, G. S., Kim, Y. H., Cho, S. W., Park, D. J., Bae, J. M., & Park, Y. J.
- Affiliations
- Seoul National University (KR)
- The Catholic University of Korea Incheon St. Mary's Hospital (KR)
- Corresponding author
- Bae, Jeong Mo
- Park, Young Joo
- Venue
- Frontiers in Endocrinology
- Publisher
- Frontiers Media SA
- Published
- 2021-05-26
- Volume
- 12
- Pages
- 664839-664839
- ISSN
- 1664-2392 (ISSN-L)
- PMC
- PMC8187942
- OpenAlex
- W3165302226
- Cited by
- 5
- References
- 41
- Citations by year
- 2025: 1 · 2023: 1 · 2022: 2 · 2021: 1
- FWCI
- 0.75
- Type
- journal article
- Language
- en
- Open access
- gold
- doi.org
- Licence
- Locations
- Frontiers in Endocrinology (publishedVersion, cc-by)
- PubMed Central (publishedVersion, cc-by)
- PubMed (publishedVersion)
- DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
- Topics
- Health Sciences › Medicine › Endocrinology, Diabetes and Metabolism › Thyroid Disorders and Treatments
- Health Sciences › Medicine › Oncology › Drug Transport and Resistance Mechanisms
- Health Sciences › Medicine › Endocrinology, Diabetes and Metabolism › Thyroid Cancer Diagnosis and Treatment
- Keywords
- hypothyroidism, LAT1, LAT2, MCT8, intestinal absorption, distal ileum, colon, brush border
- MeSH terms
- Adult, Female, Humans, Hypothyroidism, Malabsorption Syndromes, Prognosis, Thyroxine, Tissue Distribution, Case-Control Studies, Large Neutral Amino Acid-Transporter 1, Adaptor Proteins, Signal Transducing, Young Adult
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