Liothyronine (T3): What Trials Show About Adding It to Levothyroxine

Table of Contents

1. Man-Made Triiodothyronine and How It Differs From Levothyroxine
2. What the US Label Approves It For
3. The Boxed Warning on Weight Loss
4. Label Dosing, Monitoring and Side Effects
5. The Combination-Therapy Trials
6. How Many Patients Preferred the Combination
7. The Deiodinase Gene Hypothesis
8. Desiccated Thyroid Extract Trials
9. Heart Rhythm, Bone and Survival Findings
10. What Guideline Panels Currently Say
11. What Patients Report
12. What the Evidence Does Not Yet Settle
13. Key Research Papers
14. Connections
15. Featured Videos

Man-Made Triiodothyronine and How It Differs From Levothyroxine

The thyroid gland releases two hormones. Thyroxine carries four iodine atoms and is mostly a storage and transport form. Triiodothyronine carries three and is the active hormone: according to the liothyronine prescribing information, triiodothyronine and thyroxine “diffuse into the cell nucleus and bind to thyroid receptor proteins attached to DNA,” and the body’s thyroid effects “are produced predominantly by T3, the majority of which (approximately 80%) is derived from T4 by deiodination in peripheral tissues.” In other words, most of the active hormone in a healthy person is made outside the thyroid, by enzymes called deiodinases that strip one iodine atom off thyroxine.

Levothyroxine treatment relies entirely on that conversion. Liothyronine skips it. The two drugs also behave very differently in the blood:

• Absorption. The liothyronine label states that triiodothyronine “is almost totally absorbed, 95 percent in 4 hours.” The levothyroxine label gives absorption of an oral dose as 40% to 80%.
• Speed and peaks. The liothyronine label says its effect begins “within a few hours” and the maximum response comes within 2 or 3 days. In a study that gave a single 50 mcg dose of liothyronine to 12 healthy volunteers, blood triiodothyronine peaked at 2.5 hours, heart rate rose above baseline after about 5 hours, and thyroid-stimulating hormone (TSH) stayed below its starting value for 2 to 3 days. By contrast, the levothyroxine label notes that the peak effect of a given levothyroxine dose “may not be attained for 4 to 6 weeks.”
• Binding and half-life. The liothyronine label explains that triiodothyronine “is not firmly bound to serum protein,” and that thyroxine’s tighter binding to carrier proteins “partially explains the higher serum levels and longer half-life” of thyroxine. The label gives the biological half-life of liothyronine as about 2½ days.

That quick rise and fall is the central practical difference. A once-daily liothyronine tablet produces a daily peak in blood triiodothyronine that a healthy thyroid does not produce, which is why researchers designing new trials have asked for twice-daily dosing or a slow-release form (see guidelines).

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What the US Label Approves It For

Liothyronine sodium tablets were first approved in the United States in 1956. The reference prescribing information on DailyMed, last revised in May 2026, lists three uses:

• Hypothyroidism — replacement in primary (thyroid), secondary (pituitary) and tertiary (hypothalamic) hypothyroidism, whether present from birth or acquired later.
• Thyroid-stimulating hormone suppression — as an add-on to surgery and radioactive iodine in well-differentiated thyroid cancer.
• Thyroid suppression test — a diagnostic test to tell mild hyperthyroidism or an independently overactive gland apart from a normal one. The label’s test dose is 75 to 100 mcg daily for 7 days, with radioactive iodine uptake measured before and after; a drop in uptake of 50% or more indicates a normal thyroid–pituitary axis.

The label lists two limits of use: liothyronine is not indicated to shrink benign thyroid nodules or non-toxic goiter in people with enough iodine (“there are no clinical benefits,” and overtreatment may cause hyperthyroidism), and it is not indicated during the recovery phase of subacute thyroiditis. The single contraindication is uncorrected adrenal insufficiency, because thyroid hormone speeds the clearance of cortisol and can set off an adrenal crisis.

The label does not mention combination use with levothyroxine. Its own switching section describes stopping levothyroxine and starting liothyronine at a low dose. Adding a small liothyronine dose to levothyroxine is a practice studied in the trials below, not a separate labelled indication.

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The Boxed Warning on Weight Loss

Liothyronine carries a boxed warning — the strongest warning the US Food and Drug Administration puts on a label — headed “NOT FOR TREATMENT OF OBESITY OR FOR WEIGHT LOSS.” It makes three points:

• The label states that thyroid hormones, alone or with other drugs, are not for treating obesity or for weight loss.
• In people whose thyroid works normally, “doses within the range of daily hormonal requirements are ineffective for weight reduction.”
• “Larger doses may produce serious or even life-threatening manifestations of toxicity,” particularly together with sympathomimetic amines such as those used as appetite suppressants.

The overdose section describes the signs of too much thyroid hormone, adding confusion and disorientation, and reports that cerebral embolism, seizure, shock, coma and death have occurred. It notes that symptoms “may not appear until several days after ingestion.” Because liothyronine acts within hours, this warning carries more weight for liothyronine than for levothyroxine. The 2025 safety review discussed below found that the serious harms reported in the literature came from unregulated liothyronine use or pharmacy compounding errors.

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Label Dosing, Monitoring and Side Effects

The label’s dosing is for liothyronine used on its own, not as an add-on:

• Adults with hypothyroidism. A starting dosage of 25 mcg once daily, raised by 25 mcg every 1 or 2 weeks if needed; the usual maintenance dose is 25 to 75 mcg once daily.
• Older adults and people with heart disease. A start of 5 mcg once daily, raised in 5 mcg steps.
• Children. A start of 5 mcg daily, raised by 5 mcg every 3 to 4 days; the label notes that infants a few months old may need 20 mcg daily, children at 1 year 50 mcg daily, and children over 3 years the full adult dose.
• Pregnancy. Dose needs may rise; the label calls for thyroid-stimulating hormone and free thyroxine checks once pregnancy is confirmed and at least once each trimester, and a return to the pre-pregnancy dose right after delivery. It reports that post-marketing data have not shown higher rates of major birth defects or miscarriage.

The tablets come in 5, 25 and 50 mcg strengths. The combination trials used far smaller amounts than the label’s replacement doses: the LEVOLIO trial, for example, gave a mean of 5 mcg of liothyronine a day split into two doses while cutting levothyroxine by a mean of 15 mcg.

For monitoring, the label describes thyroid-stimulating hormone checks after any dose change and every 6 to 12 months once stable, and notes that total triiodothyronine is the most useful early measure before thyroid-stimulating hormone has had time to respond. In secondary or tertiary hypothyroidism, thyroid-stimulating hormone is not a reliable guide and serum triiodothyronine is used instead.

The label states that side effects “are primarily those of hyperthyroidism due to therapeutic overdosage”: palpitations, fast or irregular heartbeat, raised pulse and blood pressure, angina, heart failure, heart attack and cardiac arrest; headache, nervousness, anxiety, irritability and insomnia; tremor, muscle weakness and cramps; increased appetite, weight loss, heat intolerance, fever and sweating; diarrhea and vomiting; hair loss; menstrual irregularities and reduced fertility; and decreased bone mineral density. Warnings cover heart effects in older people and people with heart disease, worsening blood sugar control in diabetes, and bone loss from over-replacement, “particularly in post-menopausal women.” Named interactions include bile acid sequestrants (the label gives a 4-hour gap), warfarin-type anticoagulants, digitalis, tricyclic antidepressants, ketamine and sympathomimetics.

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The Combination-Therapy Trials

By the time three thyroid associations met in 2019, the 2021 consensus document reports, “fourteen clinical trials have not shown a consistent benefit of combination therapy” with levothyroxine and liothyronine. The pattern since then has been similar: blood tests and questionnaire scores move little on average, while patient preference often tilts toward the combination.

• Appelhof and colleagues, 2005. 141 patients with autoimmune hypothyroidism were randomized to continue levothyroxine or switch to levothyroxine plus liothyronine in a 10:1 or 5:1 ratio for 15 weeks. Mood, fatigue, well-being and memory tests improved in all three groups, with no difference between them. Weight fell by 1.7 kg in the 5:1 group (versus +0.1 kg on levothyroxine), median thyroid-stimulating hormone in that group fell to 0.07 mU/L, and weight loss — not the lower thyroid-stimulating hormone — was linked with satisfaction.
• Shakir and colleagues, 2021. A double-blind, three-way crossover trial in 75 people with hypothyroidism, each taking levothyroxine, levothyroxine plus liothyronine, and desiccated thyroid extract for 22 weeks. Thyroid-stimulating hormone stayed in range on all three. There was no difference in the symptom questionnaire, general health questionnaire, memory scores or depression scores, and overall preference did not differ. The one-third of patients most symptomatic on levothyroxine alone showed a strong preference for the treatments containing triiodothyronine and scored better on them.
• LEVOLIO, 2024. A double-blind, placebo-controlled trial in 141 people whose thyroid had been completely removed: 70 took levothyroxine plus liothyronine in the morning and liothyronine in the evening; 71 took levothyroxine with an evening placebo. After 6 months, sex hormone-binding globulin (used as a marker of hormone action in tissues), other tissue markers and quality of life did not differ, even though the free triiodothyronine to free thyroxine ratio was higher on the combination (0.32 versus 0.26). The combination group needed more dose adjustments because thyroid-stimulating hormone fell, without signs or symptoms of hyperthyroidism. No preference for combination therapy was found.
• Nassar and colleagues, 2024 (meta-analysis). Pooling 15 combination trials and 2 desiccated thyroid extract trials, combination therapy gave higher total triiodothyronine, lower free and total thyroxine, and lower (better) scores on the 28-item General Health Questionnaire, with no significant difference in heart rate, sex hormone-binding globulin, thyroid-stimulating hormone, cholesterol, the thyroid symptom questionnaire or the Beck Depression Inventory. Heterogeneity between trials was moderate to high.

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How Many Patients Preferred the Combination

Preference is the outcome on which the trials disagree least. In crossover trials patients take each treatment without knowing which is which and are then asked which period they preferred. The exact figures:

• The 2025 preference meta-analysis (de Lima Beltrão and colleagues): across 11 randomized trials (8 of them crossover) with 1,135 patients, 52% preferred levothyroxine plus liothyronine or desiccated thyroid extract, 24% preferred levothyroxine alone and 24% had no preference. The pooled relative risk favouring combination therapy was 2.20 (95% confidence interval 1.38–3.52). Heterogeneity was high (I² = 81%); leaving out 4 trials lowered it to 24% with a relative risk of 1.97, and crossover trials alone gave a relative risk of 2.84.
• Appelhof 2005: the study medication was preferred to usual treatment by 29.2% on levothyroxine, 41.3% on the 10:1 combination and 52.2% on the 5:1 combination. The authors noted that 44% of those preferring the combination had a thyroid-stimulating hormone below 0.11 mU/L — that is, slightly over-replaced.
• Hoang 2013 (desiccated thyroid extract versus levothyroxine): 48.6% (34 of 70) preferred desiccated thyroid extract, 18.6% (13) preferred levothyroxine and 32.9% (23) had no preference.
• Shakir 2021: overall preference did not differ between the three arms; the most symptomatic third preferred the triiodothyronine-containing treatments.
• LEVOLIO 2024: no preference for combination therapy was found.

Two things limit how far these numbers reach. First, several trials found that the patients who preferred the triiodothyronine-containing option also lost weight on it or had a lower thyroid-stimulating hormone, so preference may partly track a slightly higher effective dose. Second, roughly a quarter of patients in the pooled data preferred levothyroxine alone, so a preference for the combination is common but not universal.

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The Deiodinase Gene Hypothesis

The type 2 deiodinase enzyme converts thyroxine into triiodothyronine inside the tissues that use it, including the brain. Panicker and colleagues began from animal work suggesting that up to 80% of the triiodothyronine inside brain cells comes from local conversion of circulating thyroxine. Their hypothesis was that people carrying a less effective version of the type 2 deiodinase gene might have enough triiodothyronine in the blood on levothyroxine but too little in the brain — and so might feel better with added liothyronine.

What their 2009 study actually found, in 552 people on levothyroxine from the Weston Area T4 T3 Study:

• The less common CC genotype of the rs225014 variant (also called Thr92Ala) was present in 16% of the study population.
• On levothyroxine, CC carriers had worse baseline General Health Questionnaire scores than TT carriers: 14.1 versus 12.8 (P = 0.03).
• On combination therapy, CC carriers improved more than on levothyroxine alone, by 2.3 points at 3 months and 1.4 points at 12 months (P = 0.03).
• The variant had no effect on blood thyroid hormone levels.
• The authors wrote that the results “require replication.”

Replication has not been consistent. In 141 patients from the Dutch trial, Appelhof and colleagues found that neither the Thr92Ala variant nor a second deiodinase variant was associated with well-being, memory and thinking tests, or preference for combination therapy. In the 2021 crossover trial, Shakir and colleagues found no influence of the Thr92Ala variant on outcomes, and in LEVOLIO the genetic variants tested did not influence any outcome. The idea therefore remains a hypothesis. The 2021 consensus document asks that future trials be large enough to test deiodinase and thyroid hormone transporter variants properly — one of its 13 statements with 100% agreement.

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Desiccated Thyroid Extract Trials

Desiccated thyroid extract is dried, powdered animal thyroid gland, which contains both thyroxine and triiodothyronine. It was the original thyroid treatment and is still prescribed. Two randomized trials compared it head to head with levothyroxine:

• Hoang 2013: a double-blind crossover trial in 70 adults aged 18 to 65 on stable levothyroxine, with 16 weeks on each treatment. Symptoms and memory and thinking scores did not differ. Patients lost 3 lb on desiccated thyroid extract (172.9 versus 175.7 lb). Those who preferred desiccated thyroid extract lost 4 lb on it and had significantly better general health and thyroid symptom questionnaire scores while taking it.
• Shakir 2021: the three-arm crossover described above, in which desiccated thyroid extract caused a minor increase in heart rate and otherwise matched the other two arms for the group as a whole.

A 2024 systematic review in Thyroid (Riis and colleagues) collected two randomized trials, nine non-randomized studies and three case reports. The randomized trials found no difference in quality of life or symptom scores; the non-randomized studies favoured desiccated thyroid extract. The included studies suggested higher heart rate, lower body weight and lower HDL cholesterol on desiccated thyroid extract, but the results conflicted, and the reviewers judged the overall quality of evidence moderate to very low with little long-term safety data. In the 2024 meta-analysis by Nassar and colleagues, desiccated thyroid extract gave higher total triiodothyronine, lower thyroxine and slightly higher thyroid-stimulating hormone than levothyroxine, with no difference in heart rate, cholesterol or questionnaire scores.

A 2026 secondary analysis of the two crossover trials (143 patients in total) sorted patients by how many symptoms they had on levothyroxine. Those with high symptom scores scored lower (better) on desiccated thyroid extract and on levothyroxine plus liothyronine; those with low symptom scores did better on levothyroxine alone. The authors propose the symptom questionnaire as a way to identify who responds.

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Heart Rhythm, Bone and Survival Findings

The label’s warnings about heart rhythm and bone describe what happens with too much thyroid hormone. The question the newer studies ask is whether ordinary, monitored liothyronine use carries extra risk.

• The 2025 liothyronine safety meta-analysis (Bahl and colleagues) combined 21 randomized trials, 4 cohort studies and 27 case reports with the UK Yellow Card and US adverse event reporting databases. In the randomized trials (2,128 people) adverse events were similar on combination and levothyroxine alone (relative risk 1.22, 95% confidence interval 0.66–2.25). In cohort studies of 630,254 people, liothyronine users showed no increased risk of atrial fibrillation (relative risk 1.10, 0.74–1.63), heart failure (1.54, 0.95–2.47) or stroke (0.86, 0.11–6.75), and a lower risk of death (0.70, 0.62–0.78). Liothyronine-related harms in the published reports came only from unregulated use or compounding errors, and the adverse event database showed no increased safety signal. The abstract does not report bone outcomes.
• Bone and fractures. In a 17-year population study from Tayside, Scotland, 400 people who had ever used liothyronine were compared with 33,955 on levothyroxine alone. After adjusting for age there was no increased risk of fractures (hazard ratio 0.79, 0.49–1.27), atrial fibrillation (0.91, 0.47–1.75) or cardiovascular disease (1.04, 0.70–1.54), and no difference in bisphosphonate (bone drug) prescriptions. The same study found more new prescriptions for antipsychotic medicines among liothyronine users (hazard ratio 2.26) and a non-significant trend toward more breast cancer and antidepressant use. Median thyroid-stimulating hormone was lower in the liothyronine group (1.07 versus 2.08 mU/L).
• Dementia and survival. A 2026 analysis of health records from 1.26 million people with hypothyroidism found 27% and 31% lower relative risks of dementia and death in propensity-matched patients on combination therapy compared with levothyroxine alone (16% and 25% in the adjusted Cox model). The authors state that further studies are needed to confirm these benefits.

All the survival and dementia figures come from observational data. People prescribed liothyronine may differ from those who are not in ways the adjustments do not capture, so these associations do not show that liothyronine caused the lower risk. The heart rhythm and bone warnings on the label still describe real effects of over-replacement, and atrial fibrillation is, in the label’s words, “the most common of the arrhythmias observed with thyroid hormone overtreatment in the elderly.”

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What Guideline Panels Currently Say

• American Thyroid Association, 2014. The task force concluded that levothyroxine remains the standard of care for treating hypothyroidism and found “no consistently strong evidence for the superiority” of combination therapy or thyroid extract over levothyroxine alone. It called for long-term outcome trials of combination therapy and thyroid extracts, including subgroup effects.
• European Thyroid Association, 2012. The guideline recommends that levothyroxine alone remains the standard treatment and states that combination therapy “might be considered as an experimental approach” in adherent patients with persistent complaints despite a normal thyroid-stimulating hormone, after associated autoimmune diseases have been excluded. It suggests a levothyroxine-to-liothyronine ratio between 13:1 and 20:1 by weight, with the liothyronine split into two daily doses, stopping if there is no improvement after 3 months, and states that ready-made combined preparations (all below 13:1) are not recommended.
• ATA, BTA and ETA consensus, 2021. After a joint conference in November 2019, the American, British and European thyroid associations agreed that there was equipoise — genuine uncertainty — justifying a new trial. Of 34 consensus statements, 28 reached at least 75% agreement and 13 reached 100%. The unanimous statements call for trials that test deiodinase and transporter gene variants, enrol patients dissatisfied with current therapy who need at least 1.2 mcg/kg of levothyroxine a day, use twice-daily liothyronine or preferably a slow-release form, take patient-reported outcomes as the main result and patient preference as a secondary result, and use a placebo-controlled, double-blind parallel design.
• 2024 review in The Lancet. Taylor and colleagues describe levothyroxine alone as the standard treatment, “safe and inexpensive,” and note that 10% of patients have persistent symptoms despite normal thyroid function tests, which has led some to use liothyronine or desiccated thyroid extract.

The 2025 preference meta-analysis concluded that patients’ preference for combination therapy is strong enough to be taken into account in shared decision-making. That is the authors’ conclusion, not a guideline statement; as of this page, no major thyroid association guideline has made combination therapy a standard first treatment.

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What Patients Report

This section reports what patients say about their treatment. These are self-reports, not trial outcomes.

An online survey posted on the American Thyroid Association website and passed on to patient groups was completed by 12,146 people with hypothyroidism. Overall satisfaction with treatment had a median of 5 on a 1-to-10 scale. Among the 3,670 respondents without self-reported depression, other stressors or other medical conditions, median satisfaction was 7 for those taking desiccated thyroid extract, 6 for levothyroxine plus liothyronine and 5 for levothyroxine alone. Those taking desiccated thyroid extract were also less likely to report problems with weight, fatigue and energy. The authors note that the survey design does not explain why. Respondents were people who chose to answer a posted survey, not a random sample.

The trials above show how these reports and the trial averages can both hold: on average the treatment groups look alike, while a minority — in the 2021 crossover trial, the most symptomatic third — prefer and score better on triiodothyronine-containing treatment. The 2021 consensus document notes that, despite the trials, combination therapy “is widely used and patients reporting benefit continue to generate patient and physician interest.” The survey authors concluded that a subset of patients are not satisfied with their therapy or their physicians, and called for studies of whether the preference for desiccated thyroid extract relates to triiodothyronine levels.

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What the Evidence Does Not Yet Settle

• Who benefits. No blood test or gene test has been shown to predict who will prefer liothyronine. The deiodinase variant finding has not replicated consistently.
• Dose and timing. Most trials gave once-daily liothyronine, which produces peaks that a healthy gland does not. None of the trials summarized on this page fully matches the design the 2021 consensus asks for — twice-daily or slow-release liothyronine, in dissatisfied patients, powered for gene variants, with patient-reported outcomes as the main result.
• Long-term outcomes. The reassuring heart rhythm, fracture and survival data come from observational cohorts and drug-safety reporting systems, not from long randomized trials.
• Weight and over-replacement. In several trials, preference tracked weight loss or a lower thyroid-stimulating hormone, so part of the preference may reflect a slightly higher overall thyroid dose rather than the triiodothyronine itself.

Decisions about thyroid medicines belong with the clinician who manages them; this page reports what the label and the studies say.

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Key Research Papers

1. Jonklaas J, Bianco AC, Cappola AR, Celi FS, Fliers E, Heuer H, McAninch EA, Moeller LC, Nygaard B, Sawka AM, Watt T, Dayan CM. Evidence-Based Use of Levothyroxine/Liothyronine Combinations in Treating Hypothyroidism: A Consensus Document. Thyroid. 2021;31(2):156-182. PubMed PMID: 33276704
2. Shakir MKM, Brooks DI, McAninch EA, Fonseca TL, Mai VQ, Bianco AC, Hoang TD. Comparative Effectiveness of Levothyroxine, Desiccated Thyroid Extract, and Levothyroxine+Liothyronine in Hypothyroidism. J Clin Endocrinol Metab. 2021;106(11):e4400-e4413. PubMed PMID: 34185829
3. Hoang TD, Olsen CH, Mai VQ, Clyde PW, Shakir MK. Desiccated thyroid extract compared with levothyroxine in the treatment of hypothyroidism: a randomized, double-blind, crossover study. J Clin Endocrinol Metab. 2013;98(5):1982-90. PubMed PMID: 23539727
4. Panicker V, Saravanan P, Vaidya B, Evans J, Hattersley AT, Frayling TM, Dayan CM. Common variation in the DIO2 gene predicts baseline psychological well-being and response to combination thyroxine plus triiodothyronine therapy in hypothyroid patients. J Clin Endocrinol Metab. 2009;94(5):1623-9. PubMed PMID: 19190113
5. de Lima Beltrão FE, Carvalhal G, de Almeida Beltrão DC, de Lima Beltrão FE, Ribeiro MO, Ettleson MD, Ramos HE, Bianco AC. Treatment Preferences in Patients With Hypothyroidism. J Clin Endocrinol Metab. 2025;110(3):887-900. PubMed PMID: 39290156
6. Bahl S, Taylor PN, Premawardhana LD, Stedman M, Heald A, Dayan CM, Okosieme OE. Risk of Death and Adverse Effects in Patients on Liothyronine: A Multisource Systematic Review and Meta-analysis. J Clin Endocrinol Metab. 2025;110(11):3278-3288. PubMed PMID: 40795305
7. Brigante G, Santi D, Boselli G, Margiotta G, Corleto R, Monzani ML, Craparo A, Locaso M, Sperduti S, Roy N, Casarini L, Trenti T, Tagliavini S, De Santis MC, Roli L, Rochira V, Simoni M. Randomized double-blind placebo-controlled trial on levothyroxine and liothyronine combination therapy in totally thyroidectomized subjects: the LEVOLIO study. Eur J Endocrinol. 2024;190(1):12-22. PubMed PMID: 38124252
8. Appelhof BC, Fliers E, Wekking EM, Schene AH, Huyser J, Tijssen JG, Endert E, van Weert HC, Wiersinga WM. Combined therapy with levothyroxine and liothyronine in two ratios, compared with levothyroxine monotherapy in primary hypothyroidism: a double-blind, randomized, controlled clinical trial. J Clin Endocrinol Metab. 2005;90(5):2666-74. PubMed PMID: 15705921
9. Appelhof BC, Peeters RP, Wiersinga WM, Visser TJ, Wekking EM, Huyser J, Schene AH, Tijssen JG, Hoogendijk WJ, Fliers E. Polymorphisms in type 2 deiodinase are not associated with well-being, neurocognitive functioning, and preference for combined thyroxine/3,5,3'-triiodothyronine therapy. J Clin Endocrinol Metab. 2005;90(11):6296-9. PubMed PMID: 16144953
10. Nassar M, Hassan A, Ramadan S, Desouki MT, Hassan MA, Chaudhuri A. Evaluating the effectiveness of combined T4 and T3 therapy or desiccated thyroid versus T4 monotherapy in hypothyroidism: a systematic review and meta-analysis. BMC Endocr Disord. 2024;24(1):90. PubMed PMID: 38877429
11. Riis KR, Larsen CB, Bonnema SJ. Potential Risks and Benefits of Desiccated Thyroid Extract for the Treatment of Hypothyroidism: A Systematic Review. Thyroid. 2024;34(6):687-701. PubMed PMID: 38526391
12. Hoang TD, Patel AA, Spiro AJ, Watson NL, Shakir MKM. Use of the 36-Point Thyroid Symptom Questionnaire to Potentially Guide Optimal Thyroid Hormone Replacement Therapy. Endocr Pract. 2026;32(1):53-59. PubMed PMID: 40947017
13. Leese GP, Soto-Pedre E, Donnelly LA. Liothyronine use in a 17 year observational population-based study - the tears study. Clin Endocrinol (Oxf). 2016;85(6):918-925. PubMed PMID: 26940864
14. Beltrão FEL, Carvalhal G, Meneghini V, Matos DAR, Beltrão DCA, Andrade BARM, Beltrão FNL, Ramos HE, Ribeiro MO, Golovko G, Ettleson MD, Bianco AC. Treatment of Hypothyroidism That Contains Liothyronine is Associated With Reduced Risk of Dementia and Mortality. J Clin Endocrinol Metab. 2026;111(2):561-571. PubMed PMID: 40579157
15. Jonklaas J, Burman KD, Wang H, Latham KR. Single-dose T3 administration: kinetics and effects on biochemical and physiological parameters. Ther Drug Monit. 2015;37(1):110-8. PubMed PMID: 24977379
16. Jonklaas J, Bianco AC, Bauer AJ, Burman KD, Cappola AR, Celi FS, Cooper DS, Kim BW, Peeters RP, Rosenthal MS, Sawka AM; American Thyroid Association Task Force on Thyroid Hormone Replacement. Guidelines for the treatment of hypothyroidism: prepared by the american thyroid association task force on thyroid hormone replacement. Thyroid. 2014;24(12):1670-751. PubMed PMID: 25266247
17. Wiersinga WM, Duntas L, Fadeyev V, Nygaard B, Vanderpump MP. 2012 ETA Guidelines: The Use of L-T4 + L-T3 in the Treatment of Hypothyroidism. Eur Thyroid J. 2012;1(2):55-71. PubMed PMID: 24782999
18. Taylor PN, Medici MM, Hubalewska-Dydejczyk A, Boelaert K. Hypothyroidism. Lancet. 2024;404(10460):1347-1364. PubMed PMID: 39368843
19. Peterson SJ, Cappola AR, Castro MR, Dayan CM, Farwell AP, Hennessey JV, Kopp PA, Ross DS, Samuels MH, Sawka AM, Taylor PN, Jonklaas J, Bianco AC. An Online Survey of Hypothyroid Patients Demonstrates Prominent Dissatisfaction. Thyroid. 2018;28(6):707-721. PubMed PMID: 29620972

PubMed Topic Searches

1. PubMed: levothyroxine plus liothyronine randomized trials
2. PubMed: the DIO2 Thr92Ala variant and levothyroxine treatment
3. PubMed: desiccated thyroid extract in hypothyroidism
4. PubMed: liothyronine safety, atrial fibrillation and fractures

Connections

• Hashimoto’s Thyroiditis — the most common cause of hypothyroidism
• Levothyroxine vs NDT vs Combination T4+T3 — the three treatment options side by side
• Hypothyroidism — symptoms, causes and diagnosis
• Reverse T3 and Low-T3 Syndrome — the inactive form of the hormone
• TSH, Free T4 and Free T3 Ranges — how the blood tests are read
• Thyroid Panel — the lab tests used for monitoring
• How Your Thyroid Is Controlled — an interactive animation of the feedback loop
• Selenium for Thyroid Function — the mineral inside the deiodinase enzymes
• Drugs — every drug page on this site

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