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Ferrous Sulfate-Induced Increase in Requirement for Thyroxine in a Patient With Primary Hypothyroidism
Abstract
Recent studies have shown that under experimental conditions ferrous sulfate may reduce the gastrointestinal absorption of orally administered levothyroxine sodium in patients with primary hypothyroidism. We describe a patient who became hypothyroid while taking ferrous sulfate. The hypothyroid status was corrected by increasing the dose of levothyroxine. Subsequently, when ferrous sulfate was discontinued, the patient became hyperthyroid while taking the higher dose of thyroid hormone preparation. Since both hypothyroidism and iron deficiency anemia may coexist, additional thyroid function testing is recommended in patients treated concurrently with ferrous sulfate and L-thyroxine.
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“A need for increased LT4 while taking ferrous sulfate was observed in the case report (141).”
From Guidelines for the Treatment of Hypothyroidism: Prepared by the American Thyroid Association Task Force on Thyroid Hormone Replacement (2014) · cites this paper as [141]
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Metadata
- Authors
- MOHAMED SHAKIR, K. M., CHUTE, J. P., APRILL, B. S., & LAZARUS, A. A.
- ORCID
- CHUTE, JOHN P.
- Venue
- Southern Medical Journal
- Publisher
- Southern Medical Association
- Published
- 1997-06
- Volume
- 90
- Issue
- 6
- Pages
- 637-639
- ISSN
- 0038-4348 (ISSN-L)
- OpenAlex
- W20594385
- Cited by
- 55
- References
- 0
- Citations by year
- 2026: 1 · 2025: 3 · 2024: 1 · 2023: 1 · 2022: 3 · 2021: 3 · 2020: 2 · 2019: 2 · 2018: 2 · 2017: 3 · 2016: 2 · 2015: 2 · 2014: 2 · 2013: 1 · 2012: 1
- FWCI
- 0.70
- Type
- journal article
- Language
- en
- Open access
- closed
- Locations
- Southern Medical Journal (publishedVersion)
- PubMed (publishedVersion)
- Topics
- Health Sciences › Medicine › Endocrinology, Diabetes and Metabolism › Thyroid Disorders and Treatments
- Health Sciences › Medicine › Hematology › Iron Metabolism and Disorders
- Health Sciences › Medicine › Surgery › Thyroid and Parathyroid Surgery
- Keywords
- ferrous sulfate, levothyroxine, primary hypothyroidism, drug interactions, iron deficiency anemia, hyperthyroidism, thyroid hormone absorption, thyroid function tests, iron supplementation
- MeSH terms
- Administration, Oral, Adult, Drug Interactions, Female, Ferrous Compounds, Humans, Hyperthyroidism, Hypothyroidism, Intestinal Absorption, Thyroiditis, Autoimmune, Thyrotropin, Thyroxine, Anemia, Iron-Deficiency
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