- A low TSH (detectable but below range) is completely different from a suppressed TSH (undetectable), and only the suppressed version carries potential health risks like osteoporosis or atrial fibrillation.
- Having a low or even suppressed TSH does NOT automatically mean you are hyperthyroid. If you still have hypothyroid symptoms like fatigue, weight gain, and hair loss, you are not hyperthyroid regardless of what your TSH says.
- Many thyroid patients actually need a TSH on the lower end of the range to feel their best, because the body does not use thyroid medication as efficiently as it uses its own naturally produced thyroid hormone.
- The TSH is not a reliable standalone measure of thyroid function. Always request a full panel including free T3 and free T4 to get a clearer picture of what is happening in your body.
- If your doctor lowers your thyroid medication solely because your TSH dropped below range, and you felt great on the higher dose, advocate for yourself. A low TSH is not inherently dangerous.
As a thyroid patient, there is no doubt in my mind that you are already familiar with the thyroid lab test known as the TSH.
It would be weird if you didn’t.
Doctors primarily use the TSH test as a way to measure how well your thyroid gland is working.
But there’s one big problem with that…
It doesn’t work nearly as well as they think and probably not nearly as well as you think.
If you are someone who is relying SOLELY upon the TSH as a means to determine whether or not your thyroid medication is ‘adequate’ then you are most likely making a huge mistake.
Today we are going to talk about just that.
We will be covering…
- How your thyroid medication impacts your TSH
- Why the TSH isn’t the best measure of thyroid function in your body
- The difference between a low TSH and a suppressed TSH
- Why lowering your TSH is probably not a big deal in the long-term
- And more…
Let’s jump in…
Before we do, though, you need to know that this information primarily applies to people who are taking thyroid medication.
It does not necessarily apply to people who have a low or suppressed TSH without using these thyroid medications.
Conditions in which your own body suppresses your TSH naturally are considered on the hyperthyroid spectrum.
This information applies to people with LOW THYROID who are ALSO taking thyroid medication.
What is a Suppressed TSH?
For starters, we should talk about the exact definition of a suppressed TSH.
A suppressed TSH is the thing that your doctor is so afraid of when adjusting your thyroid medication.
In fact, I’m sure you’ve experienced a situation similar to this:
Your doctor increases your dose of thyroid medication only to find that your TSH went down farther than expected.
You feel great on this new dose of thyroid medication but your doctor is worried about your health and they say that having a low TSH is dangerous they lower your dose.
All of your symptoms are back but you are told that you are now “safe”.
Does this sound familiar?
This is pretty standard for doctors, including endocrinologists.
But, as I mentioned above, there’s one huge problem with this method of thinking about the TSH.
It’s just flat-out wrong.
But we will get to that later.
Doctors are afraid of giving you too much thyroid medication because they fear that you will become “suppressed”.
This idea refers to giving you enough thyroid medication that it lowers your TSH to a point that it is no longer detectable.
In physiologic terms, it means that your brain is no longer sending signals to your thyroid gland to produce more thyroid hormone.
When your TSH is suppressed, you are nearly 100% reliant upon thyroid medication to provide thyroid hormone to your body and cells.
So what’s the big deal with this state?
Doctors are afraid that suppressing your TSH will cause two major conditions:
#1. Osteoporosis.
And #2. Atrial fibrillation.
They also believe that if your TSH is suppressed or too low this is an indication that you are “hyperthyroid”.
As you will soon see, neither of these things is true.
What a Suppressed TSH Means
On the contrary, it’s actually quite possible for you to have a suppressed TSH and still have LOW THYROID symptoms.
And you probably know what I am talking about if you’ve ever had a suppressed TSH.
This is quite common by the way, with studies showing that at any given time as many as 30% of thyroid patients have been suppressed at some point in their life.
But let me ask you a question…
When you had a low or suppressed TSH did you feel hyperthyroid? Did you suddenly lose a bunch of weight or find that you were jittery or that your hands wouldn’t stop shaking?
Did you experience ANY of the symptoms of hyperthyroidism?
Or did you continue to have low thyroid symptoms such as weight gain, fatigue, hair loss, constipation, and depression?
I can almost guarantee that most of you experienced more of the latter.
And the reason is simple:
A suppressed TSH does NOT automatically mean that you are hyperthyroid (1)!
Let me make this as clear as possible:
It’s not possible for you to magically be hyperthyroid but NOT notice it.
You can not be hyperthyroid without having the symptoms of that condition.
If you do NOT have the symptoms then you are not hyperthyroid.
I know this topic can be confusing because I see comments from thyroid patients on a daily basis.
They are often quite confused because they are told they are hyperthyroid, due to their TSH level, while they experience nearly every hypothyroid symptom in the book.
These two things are not compatible with one another.
You are either hypothyroid or hyperthyroid, not both, and you can only be one.
The best way to figure this out is by looking directly at your symptoms (and a complete range of lab tests that includes more than just the TSH).
Degrees of TSH Suppression
Another important thing for you to understand is that not all flavors of TSH suppressed are created equal!
Let me give you an example.
Consider a thyroid patient who is taking 100mcg of levothyroxine (the weakest thyroid medication available).
With this dose, this hypothetical person has a TSH of 0.5 and is still not feeling well.
Now let’s suppose that we increase that dose of levothyroxine up to 200mcg per day.
This person’s TSH then drops down to an unnoticeable level and they are considered to have a suppressed TSH.
Now let’s take that same person and increase their dose by another 100mcg so now they are taking a total of 300mcg per day.
Does the TSH go any lower than it already was?
No, because it’s already suppressed.
But the impact that the 300mcg of levothyroxine has on the body is different from the impact that the 200mcg dose of levothyroxine has.
And yet we consider both of these patients in the same “category”.
You can also apply this thought experiment using other thyroid medications such as Cytomel.
The point here is that you can suppress the TSH using different types of medications and doses and they are NOT all the same.
The risks associated with suppressing a TSH with 300mcg are much higher than those associated with 200mcg.
And the risks associated with suppressing a TSH with 200mcg of Cytomel are much higher than those associated with 100mcg of Cytomel and so on.
There are some real POTENTIAL risks when suppressing the TSH but they are certainly not guaranteed.
What is a Low TSH?
This next part is very important if you are a thyroid patient.
I spent a lot of time talking about suppressed TSH, and there are some risks involved if you fall into that category.
But there are virtually NO downsides and no long-term consequences to only lowering your TSH.
But here’s the problem:
Doctors are just as afraid of a low TSH as they are of a suppressed TSH even though there is no evidence to suggest that a low TSH is harmful to thyroid patients.
In fact, there’s actually evidence to suggest that a LOW TSH is necessary for most thyroid patients to feel better.
The reason is complicated but has to do with the fact that the body doesn’t utilize thyroid medication the same way it uses thyroid hormone produced from a healthy thyroid gland.
So you actually need more thyroid medication for the body to use compared to what your own thyroid gland would produce naturally.
That’s a topic for another day, though!
Let me first define a low TSH for you.
I mentioned above that a low TSH is a TSH that is suppressed or non-detectable.
A low TSH is a detectable TSH but one that falls outside of the normal range that most lab tests provide.
Consider this example to help this sink in:
The standard range for a TSH test is usually somewhere between 0.5 and 4.5 uIU/mL.
A low TSH would be any TSH that falls BELOW 0.5.
So lab tests between 0.1 and 0.5 would be considered “low” but not suppressed because you can actually measure them.
A suppressed TSH will show up as something like <0.001 (which means that the value is less than the smallest amount detectable by the lab test).
A low TSH is not dangerous and does not mean that your thyroid medication is too high (necessarily)
A suppressed TSH does come with some associated risks.
For instance, there is a small risk of developing osteoporosis (2) and atrial fibrillation (3) (in certain populations).
But there are virtually no risks involved in simply LOWERING the TSH as described above.
Most doctors are afraid to do this, however, because they wrongly believe that a low TSH is indicative of a state of hyperthyroidism.
We already described why that isn’t true at all (in a previous section) and in fact, it may be necessary for your TSH to be low in order for you to get enough thyroid hormone in your body.
So when your doctor lowers your thyroid medication because your TSH is too low they are doing a disservice to you on several levels.
The first is that you might actually feel amazing on that higher dose of thyroid medication and the second is that they have tricked you into thinking what you are doing is dangerous.
What Should Your TSH “Goal” Be?
Is it possible to find the “perfect” TSH?
Or put another way, what should your “goal” TSH be?
Unfortunately, there is no straightforward way to answer this question.
I’ve seen thousands of thyroid lab tests from thyroid patients over the last 5 years and I’ve seen people feel GREAT with a TSH of 3.0 and I’ve seen people feel GREAT with a TSH of 0.2 and everything in between.
If you are looking at the TSH as a way to measure how well your thyroid is working then you are using this lab test in the wrong way.
The TSH is simply a measure of how much TSH is being produced by your pituitary gland.
It is NOT a measure of total body thyroid function nor should it be used that way.
If you are using it this way then you are using it incorrectly.
And I don’t blame you for this, it’s most likely the fault of your doctor who has drilled the importance of this relatively unimportant thyroid lab test into your head.
So what should you do instead?
I would strongly suggest that you get a complete thyroid lab panel done whenever you order a TSH.
When you use both the TSH and other important thyroid lab tests such as free T3 and free T4, you get a much clearer picture of what is happening in your body.
If your doctor is ONLY ordering the TSH as a way to measure your thyroid then it may be time to find a new doctor!
Final Thoughts
There is a big difference between a low TSH and a suppressed TSH.
A suppressed TSH does carry with it some risks to your health but these risks are relatively small and not guaranteed in all people.
On the other hand, a low TSH may be necessary for many thyroid patients to actually feel better.
And this state of TSH is NOT associated with any harm to your body long-term.
A good goal to “aim” for would be a low but not suppressed TSH while adjusting your thyroid medication,
This will allow you to not only feel better but also mitigate or eliminate any risks involved in using too much thyroid medication.
Now I want to hear from you:
What level is your TSH currently at?
Do you have a low TSH or a suppressed TSH?
Are you experiencing any symptoms or problems?
If so, what issues are you having?
Is your doctor willing to order more than just the TSH or do you need to get a second opinion?
Leave your questions or comments below!
Scientific References
#1. https://www.sciencedirect.com/science/article/pii/S2214623719301528
#2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6416151/
#3. https://pubmed.ncbi.nlm.nih.gov/22673318/
I am told I have abnormal labs from this week. I had a complete thyroidectomy about 6 years ago. I take 137mcg levothyroxine daily except Sunday. I take Liothyronine 5mcg twice daily. My recent labs say Free T3 is 4.04, Free T4 is 1.14. However, my TSH is .006. My symptoms have been weight gain, irritable, hair loss, hot and cold intolerance and insomnia. I’m certainly not thrilled with my endocrinologist but she’s the only one in my area. Is my TSH simply low or is it suppressed? I’m at my wits end and don’t know what to do anymore. Can you help?
Hi Carolyn,
Your TSH is low but you are experiencing hypothyroid symptoms which is quite common. Please see this article for more information: https://www.restartmed.com/low-tsh/
My recent labs show my Tsh as .03, T4 is 1.1, and T3 is 2.8. I’m having weight gain, hair loss, heart flutters, and trouble sleeping. I’ve been battling this for quite some time. It seems that an increase in my meds only lowers my TSH and doesn’t affect my T3 or T4 much. I need some guidance as to what to ask my doctor. I’m at my wits end.
Hi Kathleen,
You will probably have to make significant changes to your thyroid medication to help ascertain if you are hypothyroid or hyperthyroid. Small changes won’t cut it when your labs look like yours do.
Thank you for all you do .. your emails and posts have made visits to my PCP much more interesting for the past couple years.
However, I’m kinda lost here. I’m not sure where to begin, as there is so much going on, but I’ll start with current lab work:
Free T3 – 2.7 pg/mL (normal but not optimal)
Rev T3 – 12.1 ng/dL (optimal)
Total T3 – 207 ng/dL (high)
TSH – 0.04
Free T4 – 0.89 ng/dL (normal but not optimal)
Ferritin – 84.3 ng/mL (within normal lab range)
T4 – 12.4 ug/dL (within normal lab range, did not request this)
Sex Hormone Binding Globulin – 193.0 nmol/L (High)
Thyroglobulin Antibody – >2250.0 IU/mL
Thyroid Peroxidase Antibody – 24 IU/mL
My PCP lowered my NP Thyroid dose from 90 mg of NP Thyroid to 75 mg in May 2021 .. my TSH then went from 0.08 in June 2021 to the current 0.04. She wants to lower the dose again to 60 mg. She called me when she got the lab results recently, she was so concerned.
I understand that my natural thyroid meds could be affecting my TSH level, I’m not sure if Hashimoto’s does or not. I was taking 20 drops a day of 5% Lugol’s iodine for about 18 months, but it seemed to be negatively affecting my thyroid lab work, so I ramped down the dose to the point of stopping altogether. Despite the SHBG and Antibody results, these are the closest to normal thyroid results I’ve had in years.
I was incredibly energetic last winter into spring 2021, and cleaned out a decade’s worth of garden overgrowth and started over on several shade gardens and a sidewalk border. Totally unusual behavior for me. I was fighting h pylori at the time with a natural antibiotic, gave up gluten and dairy, and generally cleaned up my diet a bit more, which may or may not been a factor. However, since then I have been both fatigued and have lost weight. I’ve been moody, but can sleep well, except when I need to get up to go to the bathroom. My hair was thinning for a while, but while still thin, the drain is no longer plugged with hair. I occasionally get little irregular heart palpitations, but they’re not so often they’re concerning. My PCP thinks I’m hyperthyroid, but a comprehensive GI Map I did in Oct of 2020 revealed a pretty high level of a parasite (Dientamoeba fragilis) which could also be the cause of both fatigue and weight loss. I’m planning on doing another GI Map test in the spring, but haven’t a clue if this parasite is still in residence. Because my TSH decreased instead of increased when she lowered my dose, I’ve been inclined to think she’s wrong to want to lower it again. However, the high SHBG result suggests too much thyroid hormone. So I’m at a loss to comprehend it all.
I see her for a 6 month visit on Friday the 11th. I have a functional nutritionist who has been helping with a low SigA and some other things revealed on the GI Map, but neither she nor my primary are thyroid savvy. Before I came along, she never tested anything but TSH. She’s open to new information, and has been great about requesting anything I ask for in lab work, but the picture it all paints is fuzzy to me. Because of you, I’m not as concerned about my TSH results as she is, but the addition of that SHBG result makes me wonder now if she’s right, and I need to lower my dose.
Lost in test results ..
Hello Dr Westin Childs
I would like to thank you for sharing your expertise and knowledge. I find your informative videos have a calm, very thorough and clarifying manner to educate those of us with a variety of thyroid issues.
My story is, in 1984 I had a lump in the left side of neck and my thyroid scan I 123 200 uCi orally result was normal.
I had three doctors with three different opinions from swollen glands to an enlarged jugular vein or venous abnormality! Followup was an angiography.
I chose to undergo surgery to remove the lump August 16, 1984.
The diagnosis per the pathology report was a left neck mass 2.4cm tan nodule received fresh for frozen section diagnosis follicular neoplasm.
In the microscopic report:
Sections show a few remnants of lymph node tissue, the majority was replaced by a metastatic adenocarcinoma of the thyroid. The histologic pattern of this tumor is follicular, no papillary structures are microscopically identified. Two foci of cystic degeneration are noted. Psammoma bodies and optically clear nuclei are both identified within this neoplasm. Tumor cells are also identified within lymphatics vessels.
This case has been reviewed by entire department and agree this is a metastatic adenocarcinoma in the lymph node with a thyroid primary. No papillary areas are identified in this tumor, the presence of optically clear nuclei, psammoma bodies and the presence in a lymph node suggest to some that this is really a papillary carcinoma and would classify it as follicular variant of papillary carcinoma. Others feel in the absence of papillary structures, these criteria are inadequate to make the diagnosis of papillary carcinoma and therefore classify this tumor as follicular carcinoma.
Two weeks later, operative report in spite of a negative thyroid scan, I had a total thyroidectomy and left cervical node dissection. Eleven cervical nodes and five of these contain metastatic tumor removed.
On October 9, 1984, I had a I 131 10mCi orally for a metastatic survey for thyroid carcinoma.
October 17, 1984, I had a I 131 120mCi ablation for thyroid carcinoma.
Followup care was a whole body and bone scans. Between 1985 and 2002, I received nine whole body scans on an average of 5.0 mCi per scan and estimated five bone scans. All whole body and bone scans have been negative.
Year 2002 to present, I have ultrasounds to monitor ten lymph nodes measuring between 5mm to 9mm. No tissue remnants in the thyroid bed.
Dr Westin Childs, I do have two questions, is it normal to have so many whole body and bone scans when each previous for years are negative?
What are the side effects of having so many radioactive scans, possibly a meningioma?
Three months ago, I changed my endocrinologist of twenty two years because I relocated out of state. I felt wonderful prior to March 2022, Synthroid medication dosage 972mcg per week, I had lots of energy and no palpitations. We kept my TSH suppressed 0.01, my free T4 is usually between 1.6 and 1.9, calcium is 9.3, D3 is 61 and bone density results were normal.
I have had three appointments with my new endocrinologist whom has decreased my Synthroid dosage to 822mcg per week. I feel he is only focusing on the TSH level of which he wants it to increase. I explained as of two weeks ago at an appointment, my energy level has decreased, hair loss more than normal and feeling puffy. The doctor did not seem to be concerned how I was feeling and proceeded to actually read to me articles written regarding what the levels TSH should be. Then he stated he was reducing my Synthroid to 784 mcg per week, of which I said that is too low for me to function.
The new endocrinologist is only focusing on the TSH labs every six weeks and not the whole picture to include my freeT4.
I know my body and in three months my energy greatly decreased, so I did not reduce my Synthroid to a lower 784 mcg dosage, canceled my future appointment and informed I was no longer a patient.
I returned to my previous endocrinologist of twenty two years who has carefully monitored my labs and me and will gladly continue a long distance care program getting me back to feeling great again.
It is very sad that some endocrinologists are strictly by the lab results and do not take in to consideration the signs right in front of them of how their patient is truly feeling.
A heartfelt thank you for giving me the tools to make the proper decisions with my endocrine care!
Linda
Hi Linda,
Happy to help and glad you enjoy the information! In regards to your question, bone scans typically carry very little radiation so the risk of cancer is quite minimal. Radiation exposure is a known cancer risk but the risk increases as radiation exposure accumulates over a period of time.
TSH: 0.023
T3: 6.1
T3: 11
I’ve been on increase dose of Thyroid 90mg medication (increase since August) for 7 months and have not felt any better or noticed any improvements. If any, some symptoms are worse like bloating and acne.
Dr. Child’s,
My doctor has me suppressed with Synthroid 125mcg plus 20mcg T3 (10mcg AM & 10MCG PM) and a tsh of <0.0001 for the past five years. Is that wrong? Safe? Should I worry about that level of suppression?
I've never felt any hyperthyroidism symptoms. My new Endo is shocked and scared me by telling me this dose is dangerous for my heart. My T4 & T3 have always been in the normal range. Could you please let me know if this level of suppression would have done damage to my heart with my T3 & T4 in normal range? I was not aware of this type of risk, so would really love to have some clarification if TSH suppression puts a strain on your heart and makes it work harder? (The Endo told me this).
I'm 48 female, and had an Echocardiogram and was just diagnosed with diastolic dysfunction. I've started doing research since then and found a few articles stating tsh suppression can do this. I had no idea, I thought I'd my heart is not racing my medication was not causing an issue. I also had a completely normal dexa scan, no osteoporosis.
I'm only finding gloom and doom articles on this now that I started looking. Scared and anxious about the outcome, as I was never told this was our could be an issue from tsh suppression. In fact i trusted my doctor fully… until now and I'm scared and doubting if I've done this damage to my heart? Or if it's likely from another cause? Is 5 years with a suppressed tsh <.0001 long enough to cause diastolic dysfunction? If you could please let me know, I'd be so grateful. I'm stuck with my own thoughts and worry.
Thank you in advance.
Hello, I would love to hear your thoughts on this! My current labs are:
TSH .1 ( .3 – 3)
Free T3 3.8 ( 1.8-4.8)
Free T4 1.28 ( .8 – 1.9)
My doctor says everything looks great and is happy with my results and I think I feel good, but I’ve lost a good deal of weight. Am I taking a slight higher dose than needed? I’m currently taking 112mcg Levothyroxine. Thank you!
Hello. My TSH has been 0.005 for years. They have moved me from 150 mcg Synthyroid down to 75 mcg with no change in TSH. I keep trying to tell them nothing will change and to put my Synthroid dose higher. They insist they know better. My Free T4 is 137 and Free T3 is 3.9. Also taking 15 mcg Cytomel.
Dr. Childs,
I have Hashimoto’s and Hypothyroidism. I recently have been weened off Cytomel 5 mcg that I was taking along with my Synthroid 112. I was feeling jittery and loosing weight too fast and going off the Cytomel has helped with that. My TSH was suppressed at 0.0 for several months and since going off Cytomel, it has remained high. I do sometimes feel jumpy if I overdo too much during the day and it takes my body a while to calm down. I asked my doctor to reduce my Synthroid to 100 and he has, I am also 67 years old and would like to keep my bone density what it is. I haven’t started taking the 100’s yet, but will after I finish my last couple of 112’s. I hope my TSH doesn’t drop too low, but I guess I’ll know by the way I feel. My Hashimoto’s is under control due to no longer eating gluten, dairy or soy products and my weight has come off. It’s been a struggle, but feel that things are better in control. I also lost my taste and smell with Covid in 2022 and still don’t have it back. I am getting my 4th Stellage Ganglion Block soon and if this one doesn’t work, I ‘m loosing hope of it ever returning.
Hello!
I have had hypothyroidism for about 14 years – diagnosed in 8th grade. I have always been lean and extremely athletic, so I went under the radar of most doctors, and struggled with this for a while even after being diagnosed – many doctors would literally say “you’re skinny, you can’t be hypothyroid!” despite my obvious hypothyroid symptoms and lab results.
I worked with a naturopathic doctor for the past four years, we took a year to play around and find a dose that I felt good on. This ended up being quite a high dose – 180 mg of NP Thyroid (NDT). My TSH on this dose has stayed at 0.1, with T3 and T4 (total and free) remaining in the normal ranges. I have always monitored for symptoms of overmedication and have not noticed any. However, I moved states and am trying to find a new doctor but all are so caught up in my TSH (they want me to get EKGs done and lower the dose, or even switch to Levo/Synthroid which I tried for the first 10 years and felt miserable). I instantly get a trauma response when doctors want to lower my dose, since for the first 10 years of having this they were constantly changing my dose and every time I started to feel better, they would lower it and all my symptoms would come back (and I would gain weight instantly!). I have been tested for Hashimoto’s and do not have it (one doc was so convinced my TSH and symptoms meant I had Grave’s and was shocked when my lab results showed I didn’t have it).
I am working now with a functional medicine doctor, but he is a DC, so cannot prescribe medications so I need to find a PCP that will work with him and prescribe the medications I need.