Neither Baseline nor Changes in Serum Triiodothyronine during Levothyroxine/Liothyronine Combination Therapy Predict a Positive Response to This Treatment Modality in Hypothyroid Patients with Persistent Symptoms
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Background: Despite biochemical euthyroidism, some levothyroxine (L-T 4)-treated hypothyroid patients report persisting symptoms and some of these patients are tentatively treated with a combination of L-T 4 and liothyronine (L-T 3). Combination therapy and the appropriate choice of blood tests to monitor treatment are highly debated among specialists and patients. Aim: To evaluate whether measuring serum triiodothyronine (S-T 3) at baseline or during combination therapy can be used as an indicator of a positive effect from L-T 4/L-T 3 combination therapy. Materials and Methods: Observational retrospective study of patients (n = 42) with persisting symptoms of hypothyroidism despite L-T 4 therapy who had normal TSH levels and did not have any comorbidities that could explain their symptoms. All were then treated with L-T 4/L-T 3 combination therapy at a dose ratio of 17/1 according to European Thyroid Association guidelines. Based on patient-reported outcome, they were divided into responders and nonresponders. Results: Five patients were lost to follow-up and thus excluded. At the 3-month follow-up, 11 were classified as nonresponders and 26 as responders. At 12 months these figures had changed to 13 (35%) and 24 (65%), respectively. When comparing responders versus nonresponders, no differences were seen at baseline or during follow-up in S-T 3 and in free T 3 estimates. Further, logistic regression showed no correlation between S-T 3 and free T 3 estimates and responder/nonresponder status. Conclusion: Our data indicate that serum T 3 measurements are not suitable to predict which patient will benefit from L-T 4/L-T 3 combination therapy, and treatment response cannot be followed by repeated T 3 measurements either.
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Neither baseline serum T3 levels nor serum T3 levels while on therapy seemed significant with respect to preference for combination therapy in one small study.
“Neither baseline serum T3 levels nor serum T3 levels while on therapy seemed significant with respect to preference for combination therapy in one small study.”
From Evidence-Based Use of Levothyroxine/Liothyronine Combinations in Treating Hypothyroidism: A Consensus Document (2021) · cites this paper as [68]
Neither baseline serum T3 levels nor serum T3 levels while on therapy seemed significant with respect to preference for combination therapy in one small study.
“Neither baseline serum T3 levels nor serum T3 levels while on therapy seemed significant with respect to preference for combination therapy in one small study.”
From Evidence-Based Use of Levothyroxine/Liothyronine Combinations in Treating Hypothyroidism: A Consensus Document (2021) · cites this paper as [68]
The study examining baseline and on-therapy serum T3 levels and preference for combination therapy was not prospectively conducted and the timing of blood sampling was not standardized.
“However, this study was not prospectively conducted and the timing of blood sampling was not standardized [68].”
From Evidence-Based Use of Levothyroxine/Liothyronine Combinations in Treating Hypothyroidism: A Consensus Document (2021) · cites this paper as [68]
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- Authors
- Medici, B. B., la Cour, J. L., Michaelsson, L. F., Faber, J. O., & Nygaard, B.
- Affiliations
- University of Copenhagen (DK)
- 1Department of Endocrinology, Herlev University Hospital, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Venue
- European Thyroid Journal
- Publisher
- Bioscientifica
- Published
- 2017-01-19
- Volume
- 6
- Issue
- 2
- Pages
- 89-93
- ISSN
- 2235-0640 (ISSN-L)
- 2235-0802
- PMC
- PMC5422753
- OpenAlex
- W2576169452
- Cited by
- 25
- References
- 18
- Citations by year
- 2025: 3 · 2024: 3 · 2023: 3 · 2022: 1 · 2021: 4 · 2020: 3 · 2019: 5 · 2018: 2 · 2017: 1
- FWCI
- 2.38
- Type
- journal article
- Language
- en
- Open access
- bronze
- doi.org
- Locations
- European Thyroid Journal (publishedVersion)
- PubMed Central (publishedVersion)
- PubMed (publishedVersion)
- Research at the University of Copenhagen (University of Copenhagen) (publishedVersion, other-oa)
- Funders
- Herlev Hospital
- Topics
- Health Sciences › Medicine › Endocrinology, Diabetes and Metabolism › Thyroid Disorders and Treatments
- Health Sciences › Medicine › Surgery › Thyroid and Parathyroid Surgery
- Health Sciences › Medicine › Endocrinology, Diabetes and Metabolism › Thyroid Cancer Diagnosis and Treatment
- Keywords
- hypothyroidism, levothyroxine, liothyronine, combination thyroid hormone therapy, serum triiodothyronine, free triiodothyronine, treatment response prediction, patient-reported outcomes, thyroid function monitoring
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