Link to original tweet by ThyroidFederation:
twitter.com/ThyroidFed/stat...
"The use of combination therapy with liothyronine and #levothyroxine in Asian patients was looked at and found that use of liothyronine was linked with higher incidence of heart failure and #stroke in those with a longer duration of liothyronine use and history of thyroid #cancer.
Link to Abstract of study, full text is behind paywall:
liebertpub.com/doi/10.1089/...
Heart Failure and Stroke Risks in Users of Liothyronine With or Without Levothyroxine Compared with Levothyroxine Alone: A Propensity Score-Matched Analysis
Wook Yi, Bo Hyun Kim, Mijin Kim, Jinmi Kim, Myungsoo Im, Soree Ryang, Eun Heui Kim, Yun Kyung Jeon, Sang Soo Kim, and In Joo Kim
Published Online:8 Jul 2022doi.org/10.1089/thy.2021.0634
"Abstract
Background: Combination therapy with liothyronine (LT3) and levothyroxine (LT4) is used in patients with persistent symptoms, despite being administered an adequate dose of LT4. LT3 may also be used in some thyroid cancer patients preparing for radioactive iodine therapy. However, there is a controversy regarding the safety of LT3 use, and there has been no definite evidence of long-term safety of LT3 therapy in Asian populations. The aim of this study was to examine the long-term safety of LT3 therapy using the Common Data Model (CDM).
Methods: We conducted a retrospective multicenter study across four hospital databases encoded in the Observational Medical Outcomes Partnership (OMOP) CDM. LT3 users were defined as those who received an LT3 prescription for at least 90 days (with or without LT4), and their safety outcomes were compared with those in LT4-only users after 1:4 propensity score matching. Safety outcomes included the incidences of osteoporosis, cardiovascular disease, cancer, anxiety disorder, and mood disorder.
Results: We identified 1434 LT3 users and 3908 LT4-only users. There was a statistically significant difference in the incidence rate of safety outcomes between LT3 users and LT4-only users. The risks of heart failure (incidence rate ratio [IRR] = 1.664, 95% confidence interval [95% CI] 1.002–2.764, p = 0.049) and stroke (IRR = 1.757, CI 1.073–2.877, p = 0.025) were higher in LT3 users than in LT4-only users. When subgroup analysis was performed according to the presence/absence of thyroid cancer history and duration of thyroid hormone replacement, the risk of heart failure was higher in LT3 users with a history of thyroid cancer and those who underwent ≥52 weeks of LT3 therapy. In addition, the risk of stroke was higher in LT3 users without thyroid cancer history and those who underwent ≥52 weeks of LT3 therapy.
Conclusions: The use of LT3 was associated with increased incidence of heart failure and stroke in patients with a longer duration of LT3 use and history of thyroid cancer. Therefore, clinicians should consider the risk of heart failure and stroke in thyroid cancer patients with long-term use of LT3. These findings require confirmation in other populations."
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diogenes .. (wondering if you can access full details) ....if so , do you have any thoughts on the validity / relevance of this evidence ? ..( i notice Johannes Dietrich had replied to thyroid Fed via tweet to ask for details, so wondered if you were aware of this paper. )
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@'Everyone else' ..... as shown below in an Endo's letter that a forum member recently shared with me, this paper is already being quoted by Endo's as evidence .....(in this case the endo is relating it to Armour thyroid use which is a bit of a stretch,) but i expect it will soon be used by many endos' to put people off trials of combination therapy , so i think we need to be looking for ways to counter this paper ... ie does it prove causation over association ?
"Dear Dr •••••••••
I reviewed this lady who has difficult hypothyroidism following treatment for differentiated thyroid cancer. Over the last few weeks •••••••• has built up the dose of her Armour Thyroid to *****// . In addition to the previously documented theoretical risks of taking Armour Thyroid, of atrial fibrillation and it's consequences including stroke and death, cardiovascular disease, reduced bone mineral density, osteoporosis and fracture risk,
I have made ****** aware of new data that has emerged from a study in Korea which looked at patients treated with Liothyronine, either alone or in combination with thyroxine compared to patients on monotherapy. The summary findings were an increased incidence of heart failure and stroke in patients treated with Liothyronine In patients taking T3 for one year or longer there was an increased incidence of heart failure in patients thyroid cancer and an increase risk of stroke in patients who didn't have thyroid cancer compared to Levothyroxine monotherapy. I have made her aware of these findings and while they need confirmation in other studies they should be considered in clinical decisions regarding the use of T3 containing medications."