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How to Use Liothyronine (T3) in Hypothyroidism

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​Liothyronine (T3) is ​the most potent thyroid hormone that you can take.

It is rarely prescribed by most doctors, which is unfortunate, because it can significantly improve your hypothyroid symptoms and overall quality of life.

The symptom improvements can include ​improved energy, weight loss, and even a reduction in depression.

​Learn who could benefit from using liothyronine, how to use it safely, and lots more in this article...

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What is Liothyronine?

​In order to understand liothyronine, it is important that you ​understand the basic physiology of the thyroid. You can read more in depth about it by clicking here.

Liothyronine is T3.  T3 is one of the 2 main circulating thyroid hormones in your bloodstream.

T4 is the inactive thyroid hormone.  The vast majority of hormone made by the thyroid gland is T4.  

T4 itself ​has no activity in the body.  In order for it to be​come an active hormone, it must be converted into T3​.  An iodine molecule is cleaved off of the T4 by an enzyme called a deiodinase, which ​results in the production of T3.

T4 can be looked at as the storage reservoir for thyroid hormone in ​your body.  When your body needs more active thyroid hormone, it can convert the T4 that is circulating in the blood into active T3.

​By understanding that T4 is the inactive form of thyroid and T3 is the active form, it then makes sense why ​oral T3 medication is much more potent than oral T4 medication.  In fact, it is about 3-4 times more potent.

Liothyronine vs. Levothyroxine

​If Liothyronine is so powerful, then why don't more doctors prescribe it?

​Most doctors simply were not taught how to prescribe T3 medication and manage patients that are taking it.  They ​were also not taught which labs need to be monitored and how to interpret those test results.

I ​was personally NEVER taught about T3 medications in my many years of training.  I have had to learn about it myself through attending multiple medical conferences, reading tons of literature, and asking doctors with experience ​prescribing it how they use it.

It is simply assumed by most doctors that all patients have no issues with converting T4 to T3.  If that was the case, every patient could just take a T4 only medication such as Synthroid, levothyroxine, or Tyrosint and it would seamlessly be converted to T3 when the body needed it.

Wouldn't that be easy?

However, most people with thyroid issues have a reduced ability to convert T4 to T3.  Instead, much of the T4 is converted into the anti-thyroid metabolite reverse T3 which results in a condition called reverse T3 dominance.  This is usually due to chronic inflammation in the body and/or a deficiency of nutrients such as iodine, selenium, or zinc.

​That is why you may be on a ​good dose of a T4 only medication which results in a normal ​TSH and T4 level, yet you still have symptoms of hypothyroidism.

In those situations, when used and monitored properly, liothyronine can be a safe and extremely effective medication to treat your hypothyroidism and improve your symptoms.

One study showed that replacing T4 with T3 resulted in weight loss and greater thyroid action on lipid metabolism, without an increase in side effects.

Who Should Use Liothyronine?

​Not everyone who takes thyroid medication necessarily needs to take liothyronine.

​Besides having hypothyroidism, if you are otherwise healthy, energetic, and feel great, your conversion of T4 to T3 is probably adequate and you may not need to change from your T4 only medication.

Now, for the other 99% of you (ha!), you may want to get a complete thyroid panel so that you can truly assess the T4 and T3 levels in your body:

​You should also consider getting a sex hormone binding globulin level (SHBG), which can also help give you an idea of the thyroid levels in your body (if you are on oral birth control pills or estrogen or if you smoke, this test will not be helpful).

​If your reverse T3 level is >15, your free T3 level is ​<3.5, and/​or your SHBG level is <20 in men or <60 in women (who aren't taking oral estrogen), then your T3 level is inadequate and you ​may want to consider adding T3 in some form to your regimen. 

Below is a general list of people who may need to add T3 to their thyroid medication regimen:

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    Patients with low serum levels of free T3 (<3.5)
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    Patients with high levels of reverse T3 (>15)
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    Patients with "normal" TSH and T4 levels but still remain symptomatic despite taking T4 only thyroid medication
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    Patients with chronic inflammatory conditions such as an autoimmune disease, insulin resistance, and leptin resistance
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    Patients that have persistent difficulty with weight loss
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    Patients with treatment resistant depression and treatment resistant bipolar disorder

​This is by no means an exhaustive list, but it includes the majority of patients that m​ay benefit from taking T3.

​What about Natural Dessicated Thyroid (NDT)?

​If you are currently taking a T4 only medication (Synthroid, levothyroxine, or Tyrosint), changing to an NDT medication such as Armour Thyroid, NP Thyroid, or Nature-throid may be the easiest ​thing to try to increase your T3 level.  In fact, that is usually the first thing I will do for patients.

NDT is about 80% T4 and 20% T3.  While that is certainly better than a ​medication with 100% T4, that may still be too much T4 which ​could result in a high level of reverse T3.

If​ you are taking an NDT medication and your reverse T3 levels are too high and your free T3 levels are too low, you may need to reduce your NDT dose (at least temporarily) and add a small dose of liothyronine in order to "flush out" the reverse T3 which will allow the T3 ​levels to rise to optimal levels.

Liothyronine for Weight Loss

​Liothyronine may cause weight loss but it should NOT be used as a weight loss medication.

​If used for weight loss in patients without thyroid dysfunction, it could cause some unpleasant and even dangerous side effects.

However, liothyronine may help with weight loss in patients with hypothyroidism.

T3 may cause more weight loss than T4 because of how it interacts with fat cells and other hormones in the body.

T3 directly increases mitochondrial energy production and increases thermogenesis and fat burning potential.

Liothyronine for Depression

​Liothyronine can also reduce symptoms of depression.

Low thyroid levels (hypothyroidism) are known to commonly result in symptoms of depression.

What you may not know is that adding liothyronine to an antidepressant ​can improve mood and cognitive function even when the thyroid function is normal.

The exact mechanism is not fully understood, but it is believed that some patients with depression may have subclinical hypothyroidism that is not bad enough to be detected on standard lab tests but still causes typical symptoms of depression.

Therefore, by treating those patients with liothyronine, it may correct those subtle thyroid abnormalities in the brain which will help resolve the depression symptoms.

T3 has also be shown to increase the receptor sensitivity to serotonin and increase the synaptic concentrations of serotonin.

Since the most commonly used antidepressants are only successful in treating depression in about 50% of cases, the addition of liothyronine ​is a viable option to consider, especially in "treatment resistant" cases.

If you are on a T4 only thyroid medication and are still suffering from depression, adding liothyroinine to your T4 medication may significantly improve mood and neuro​psychological function.

​How to Raise T3 Levels

​The whole point of even ​discussing liothyronine is because we want to raise the ​active thyroid levels (T3) in the body to optimal levels.

​Taking T3 medication (liothyronine) will obviously accomplish that goal.  There are ​also some natural things that should be considered that will result in increased levels of T3.  Let's discuss those ​as well as how to take ​liothyronine...

​1. Naturally Increase T4 to T3 Conversion

​The conversion of T4 to T3 is dependent on a few nutrients.  

​It is common for people to be deficient in these nutrients because they may be lacking in their diet or they may have gut issues such as leaky gut that reduce the absorption of the nutrients.

Some of the most important nutrients include:

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    Zinc - Zinc has been shown to improve conversion of T4 to T3, acts and a strong anti-inflammatory, and reduce oxidative stress.  Zinc deficiency is VERY common in the US. Standard zinc supplementation is also inadequate because it does not have zinc bound to picolinic acid (which is the most absorbable form of zinc).  Doses of 30-60mg per day are recommended.  It is important to take it with selenium.
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    Selenium - Selenium can improve thyroid conversion, act as an anti-inflammatory, and help balance the immune system.  It is also very helpful if you have an autoimmune thyroid issue such as Hashimoto's.  Doses of 200-400mcg per day are recommended. Best if taken with zinc.

​2. Naturally Lower Reverse T3 Levels

​Another way that you can raise T3 levels and improve its function is to lower reverse T3 levels.

Remember, reverse T3 is the anti-thyroid metabolite that binds to thyroid receptors on the cells but blocks their function.

By reducing the amount of reverse T3, it will in effect improve T3 function.

So how do you do it?  Address the issue that is causing the reverse T3 level to be increased in the first place.

Easier said than done, but below is a list of common issues that result in elevated reverse T3 levels:

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    Reduce Inflammation - Inflammation from any cause will increase reverse T3 levels and reduce thyroid function.  Checking ESR and CRP lab tests will indicate how much inflammation is present.  If those test are elevated, consider taking anti-inflammatory supplements such as tumeric, fish oil, and quercetin+bromelain.
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    Fix Your Gut - ​Treating conditions such as leaky gut or SIBO are essential to improve your thyroid function.  Up to 20% of thyroid conversion occurs in the gut, plus absorption of nutrients that are vital to normal thyroid function may be impaired.  About 50% of thyroid patients have SIBO/SIFO and don't even know it.  Read more about it here.
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    ​Lower Your Insulin Level - High insulin and sugar levels inhibit the ​T4 to T3 conversion process and ​contribute to weight gain.  If your fasting insulin is >5, you most likely have insulin resistance which much be addressed.  Supplements that help reduce insulin resistance include alpha-lipoic acid, berberine, and chromium.
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    Lower Your Leptin Level - Leptin is another hormone that is usually involved with weight loss resistance.  It also reduces thyroid function by increasing inflammation in the body which impairs the T4 to T3 conversion process.  ​Read more about how to reduce it here.
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    Stop Extreme Dieting - If you are eating less than 1500 calories per day just to maintain your weight, you are damaging your metabolism and lowering your T3.

​3. Short-acting Liothyronine (Cytomel)

​Cytomel is the brand name for liothyronine, but over the past few years generic versions have become available that are less expensive.  ​

Liothyronine is available in 3 strengths - 5mcg, 25mcg, and 50mcg.  I personally have never prescribed the 50mcg dose.  

​Typically, the 5mcg dose is prescribed first, then it may be increased to 10mcg (2 tablets) depending on the patient response and labs.  If more is needed, usually 1/2 pill of 25mcg is given, then possibly a full 25mcg tablet.

- Liothyronine/levothyroxine in Combination

​This is by far the most common way that liothyronine is used.  Fortunately, medical providers are becoming more comfortable using it so its use is expanding.

Liothyronine is added to the patient's current dose of T4 medication (levothyroxine).  

Remember, liothyronine is 3-4 times more potent than levothyroxine, so you will need to be aware of any side effects and your labs will need to be monitored closely.  

If your TSH is suppressed excessively, it may be necessary to reduce your dose of levothyroxine.

- Liothyronine only

​Most physicians will not be comfortable prescribing liothyronine by itself.

​This is because most medical committees recommend using a T4 thyroid medication as first-line treatment of thyroid issues.

However, many patients ​with weight loss resistance, leptin resistance, and other hormone imbalances may benefit from using T3 by itself.

T3 medication can be used temporarily to boost the body back into action or it can also be used long-term.

As long as it is used correctly and monitored closely there should not be any long-term consequences in using it.

If you are interested in using it, you must find a doctor with experience in prescribing it, and you must be willing to get regular lab tests and follow-ups with your doctor.

4. Sustained-Release (SR) T3

​Occasionally patients may be extremely sensitive to T3 medication.  In those situations, it may be necessary to have a compounding pharmacy ​make a sustained-release ​form of T3.

The sustained-release formulation will ​allow the T3 to be released ​gradually over a longer period of time which will reduce the side effects that the T3 may cause.

Liothyronine Side Effects

​Some patients tend to be very sensitive to T3 medication.  This usually causes them to feel jittery or anxious when they start the medication.

If you have a history of being sensitive to other medications, you need to let your doctor know before starting T3.  You can probably still take it, but you will need to go "low and slow" with it.

As a general rule, I have found that women tend to be more sensitive to T3 than men, although there are certainly exceptions with both.

The side effects of liothyronine seem to mirror those caused by hyperthyroidism.  These include:

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    Jitteriness - usually dose-dependent and from taking too much
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    Palpitations - usually a sign that the dose is too high
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    Nausea 
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    Hair Loss - usually temporary and resolves in 3-6 months
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    Headache - usually an indicator that the dose is too high
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    Tremor - usually dose-dependent
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    Sensitivity to Heat - and indicator that the dose is too high
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    Anxiety - an indicator that the dose is too high

​If you develop any of these symptoms you should notify your prescribing doctor and discuss treatment options.

Summary

​Liothyronine is a T3 only medication.

It is the most potent thyroid medication available.

When used correctly and closely monitored, liothyronine is extremely effective in treating hypothyroidism and reducing symptoms.  It typically causes some weight loss as well.

It can also be used to treat resistant depression.

​Now it's your turn...

Have you ever taken liothyronine?  If so, what were the results?

Leave any questions or comments below.

About the Author Dr. Jeff Whelchel

Dr. Whelchel is a family physician who specializes in functional medicine, especially hormone optimization. He has over 20 years experience in private practice managing patients with various medical issues. His passion is helping patients reach their full potential of wellness and quality of life. He grew up in the Texas Panhandle where he currently lives. He is married and has 3 awesome children.

Leave a Comment:

22 comments
Kim stavenhagen says March 6, 2018

Hi Dr Whelchel,would this be a better choice for me.

Reply
    Dr. Jeff Whelchel says March 11, 2018

    Hi Kim. We need to sit down and look at your labwork. If you reverse T3 is still >15 and your free T3 is <3.5, we may need to consider adding some liothyronine.

    Reply
Gary says March 7, 2018

I too wonder if this would be better for me.

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    Dr. Jeff Whelchel says March 11, 2018

    Hi Gary. We can sit down sometime and look at your thyroid labs and make a decision.

    Reply
Mercy says March 12, 2018

So helpful..bringing this into my nurse practirioner tomorrow!

Reply
    Dr. Jeff Whelchel says March 13, 2018

    Thank you for your comment. I hope it helps!

    Reply
Nikki Hoxie says March 20, 2018

I am blessed to have you as my doctor. Thank you for this most helpful article. You are the best!

Reply
    Dr. Jeff Whelchel says March 20, 2018

    Thank you Nikki. You are a special person to me.

    Reply
Sydney says July 5, 2018

Thank you for this blog. For 14 years after Kaiser changed my 30 yr- Synthroid prescription to a generic I began having carpal tunnel symptoms, acid reflux, muscle pains and stiff fingers, numbness in my hands, swollen knuckles and I would beg every doctor to run a T3 panel to no avail. I left Kaiser and an Endo Prescribed Armour but still didn’t run a rev T3 and things got better until Armour changed it’s formula and my TSH spiked to 19. I went back on Synthroid and symptoms returned & increased, adding headaches, heart flutters, insomnia, fatigue and depression. More recently my family physician took into account all my symptoms and ran a rev T3 since I explained I had read about this after I had 2 recent surgeries (no cancer).

He took the time to study and the rev T3 test came in 26.4. Reading your blog has given me more understanding of the road ahead. Thank you, again. 🤙

Reply
    Dr. Jeff Whelchel says July 5, 2018

    Hi Sydney. I’m glad that I can be of assistance. I hope you get the answers and help that you need and deserve.

    Reply
Vicki says July 5, 2018

I tried the T3 it caused terrible hot flashes.

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    Dr. Jeff Whelchel says July 5, 2018

    Hi Vicki. Sorry to hear that you had some side effects. T3 isn’t for everyone. It can cause some symptoms in some people. Many of those folks do better with a sustained-release T3 that can be made by a compounding pharmacy. You should discuss it further with your doctor.

    Reply
Jeanna says July 9, 2018

How do I get the pills

Reply
    Dr. Jeff Whelchel says July 9, 2018

    Hi Jeanna. You will need to see a doctor that is comfortable with prescribing liothyronine. If your current doctor isn’t you may need to change if you feel it could help you. I would suggest going to ifm.org and click on “Find a practitioner.”

    Reply
Christine says August 7, 2018

Thanks for posting this. For years I have been on compounded slow-release T3 because I can’t handle T4 (also makes me irritable and jittery). However, I am super-senstitive to the medication and can only take 9mcg. If I try to increase my dose to even 9.5mcg, I start to see the same irritable and hyperthyroid symptoms. However, my free T3 is 2.8 and I am still fatigued, low energy, difficulty falling asleep, have exercise intolerance, varying degrees of brain fog. I’m wondering if you have had success with people taking some in the morning and some at night? Or would it be possible to experiment with slow release T3 and regular cytomel? I don’t know how fast the regular Cytomel is metabolized. I am waiting to see my doc but wanting to see if you have any insights/case studies on this.

Thanks!

Reply
    Dr. Jeff Whelchel says August 16, 2018

    Hi Christine. I am sorry you are so sensitive to thyroid medication. That happens in quite a few of my patients.

    Yes, you could try splitting your T3 dose, taking 1/2 in the morning and half at bedtime. Make sure you haven’t eaten for a couple of hours before taking it. I’m afraid that you would most likely be extremely sensitive to Cytomel. You might also look at trying a different T4 medication. Many of the generic T4 meds have fillers that can cause side effects. Tyrosint in a T4 only medication that is more pure than levothyroxine or Synthroid.

    Reply
danita says August 28, 2018

I have high RT3. How do I make an appointment with you?

Reply
    Dr. Jeff Whelchel says August 28, 2018

    Hi Danita. I am currently not accepting new patients in my regular practice. You are welcome to join my online consulting membership. You can read more about it here. http://healthyhormones.us/online-membership/

    Reply
Lulu van Aswegen says October 18, 2018

I started taking liothyronine 2 weeks ago in combination with levothyroxine (I’ve been taking for at least a decade). My hypo symptoms are still debilitating. When can I expect the new meds to take effect? Please advise.

Reply
    Dr. Jeff Whelchel says October 21, 2018

    Hello. Most thyroid takes a minimum of 2 weeks to start working, but they won’t reach their full level until 4-6 weeks. Try to give it a little more time. If you don’t notice any improved by then, you need to consider other causes besides thyroid, including adrenal issues, low testosterone, etc. Good luck.

    Reply
Arezo says October 20, 2018

Hi many thanks for all this information. I have hashimoto’s and have TSH of 29 despite being on 150mcg Levothyroxine since many years. Have enormous difficulty to loose weight. Is there any conversion calculation from 150 mcg T4 to only T3. I would like to reduce T4 and stop it for some time as it seems not to work anyway.

Reply
    Dr. Jeff Whelchel says October 21, 2018

    I don’t typically recommend stopping T4. You just need to add some T3 to it, either by adding liothyronine to the levothyroxine or changing to a natural desiccated thyroid such as Armour, NP Thyroid, or Nature-throid. All of that should be done under the guidance of a medical provider with experience using them. I hope you get some relief soon!

    Reply
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