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What do these thyroid tests mean?

I have been on Synthroid for 40 years. I was taking 100mcg daily. My TSH test was 0.25L 7 years ago. I once had my dosage reduced and gained 20 lbs in a month so I was hesitant. We agreed to keep the dose the same but just skip one day per week. That worked fine until recently. My TSH in November was 0.05L and the Doctor reduced my dose to .75mcg 7 days a week. My current test came back with my TSH 0.19L. My T3 and T4 were normal. I think that 0.19L is borderline normal. Any opinions on what should be done now? So confusing. I am concerned to lower the Synthroid when T3&T4 are normal.
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Avatar universal
I agree with telus2 that the average thyroid gland secretes about 94 - 110 mcg of T4 daily.  Along with that the gland also secretes 10 - 22 mcg of T3, which is vital as stated.   When taking thyroid med orally the absorption is only about 80%, so a full daily replacement amount of T4 would require about 120 - 128 mcg of T4 and about 12 - 28 mcg of T4.  Since you are taking only 75 mcg of t4 there is no way that will get you to an adequate level of Free T4 and Free T3.    This is especially true since taking T4 med only typically results in reduced conversion of T4 to T3.       This is why so many patients find that they need a source of T3 in their med to adequately raise their Free T3 level.    An adequate Free T3 level is most important  since symptomatic change has been shown to be mainly associated with Free T3 and less with Free T4.

If you are going to give the doctor info to attempt to persuade him to treat clinically rather than based on TSH I also suggest that you click on my name and then scroll down to my Journal and give him a copy of the Overview to my paper on Diagnosis and Treatment of Hypothyroidism: A Patient's Perspective.   The paper explains all this and provides extensive evidence that a suppressed TSH does not mean hyperthyroidism unless there are accompanying hyper symptoms due to excessive levels of Free T4 and Free T3.    That might slow down the impetus to reduce your med when it actually needs to be increased and perhaps also needs some T3 added.   And don't forget the importance of Vitamin D, B12 and ferritin.  
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Avatar universal
You are not being well served by your doctor for your thyroid problems. Your best bet would be to find a new doctor. If that is impossible for you, then try asking your doctor to refer you to an endocrinologist and hope that the endo is better than the doctor. The reason to ask for a referral is that your TSH should not be so low with such low doses of Synthroid that you are taking.

What your doctor is missing (and possibly you) is that your T3 is NOT normal. Normal people have T3 at the middle of the reference range (50% of range) - for your total T3 the middle is 128.5 and yours is only 92 which is only 15% above the bottom of the range - that is not normal - that is LOW.  Unfortunately a lot of doctors do not realize that. T3 is the thyroid hormone that does all of the work in your body so if T3 is low you get hypothyroid symptoms - such as muscle pain, fatigue, weight gain, and more sensitive to cold temperature like you are having.

Your doctor is also missing the fact that a normal person's body makes 90 - 100 mcg of T4 daily. So to give you only 75 mcg of Synthroid/T4 daily (or less) is clearly not enough! If I was you I would go back to 100 mcg immediately and get new lab tests in a month.

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The doctors nurse did call me last week to say my TSH was still not good and the doctor wants to lower the dosage again. I said I am really not comfortable doing that . I asked for T3 free test to be done also and she said she would have him call me but he never did. I am going to make a copy of what you wrote and drop it off for him to look at. I am curious as to what he says/does.
Avatar universal
By the way I would not worry about the possibility of Erythromelalgia at this point.   Get the other issues corrected and then you can reassess.  
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Avatar universal
TSH is a pituitary hormone that is affected by so many things that  it is useful as an indicator of thyroid status only when at extreme levels in the untreated state., indicating  Hashimoto's Thyroiditis.      When you start on thyroid med, as I explained above, TSH is basically a wasted test.    Doctors don't understand what I explained about a suppressed TSH, however, so they want to decrease thyroid med when the TSH becomes too low for them to be comfortable.    That is wrong.   A good thyroid doctor will increase your thyeoid  medication enough to relieve hypo symptoms, without increasing to the point of causing hyper symptoms.     That sweet spot is called "clinical euthyroidism", which should be the whole objective of treatment, not biochemical euthyroidism, which means having TSH within range.  

It is doubtful that your thyroid hormone levels were adequate even at 100 mcg of T4 med.  After the reduction to 75 mcg, predictably you felt worse.   Taking away one day of the 75 mcg meant a further reduction on average of almost 11 mcg per day, which would be worse yet for you.   Your current lab results are inadequate.  Your Free T4 is okay at mid-range, but if your Total T3, which is only 16% of its range,  is indicative of your Free T3,  then that is the main reason you are having those hypo symptoms and feeling so bad.   There are recent scientific studies that have quantified for the first time the effect of Free T3 on symptoms.   They found that symptom change is mainly related to Free T3 and less with Free T4, and hardly any  with TSH.  

You might find my similar experience interesting.   I was hypo for around 40 years.  It took me a long time to convince my doctor because my TSH was "within range".   Finally I located this forum and learned about the importance of Free T3.   Got my FT3 tested and confirmed as low in the range, due to poor conversion of the T4 in the  200 mcg of Synthroid I was on.  Convinced that doctor to switch me to a desiccated type med containing both T4 and T3.  After some tweaking of dosage that got my FT4 just below mid-range, and FT3  about 70% of its range, I felt better than I could ever remember.   Of course everybody is different and may need different levels of FT4 and FT3.  My point is the importance of Free T3 and that doctors usually don't even test for it and don't pay any attention to symptoms or FT3.  

So you need to take info I can direct you to and give it to your doctor and ask to be treated clinically, as needed to relieve symptoms.  If the doctor resists or refuses, then you will need to find a good thyroid doctor that will do so.   If you will give us your location perhaps we can suggest a doctor in your general area who has been recommended by other thyroid patients.    Also at first opportunity you need to get tested for both Free T3, Reverse t# (at least once) and cortisol and ferritin.   Both your Vitamin D and B12 are lower than optimal.  D should be at least 50 ng/ml, and  B12 in the upper part of its range.  So you need ot supplement for both of those to optimize.   For info ferritin is a storage form or iron and it should be at least 100.  
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The recent decrease was small. I was taking 100mcg 6 days a week. About 7 years ago my TSH was low and the Doctor wanted to reduce my dosage which I did not want to do because when I was previously reduced I gained 20 lbs in a month so the Doctor suggested skipping a day per week which I have done for the past 7 years. Last year was the first time my TSH was low 0.02L (2018) In November 2019 it was 0.05L and that is when he changed it to 75mcg but 7 days week so the reduction in dosage went from 600mcg week to 525 week. Recent test was 0.19L .I agreed to it because my hair was falling out alot and I did not feel well. I also thought maybe taking the medication 7 days a week may be better. I really feel no difference over these 8 weeks except for my knuckles are more painful and swollen and I have some odd muscle pain in my thigh. I missed the doctors call the other day and I know he is going to tell me my TSH is still not good and to lower the dose again. When I once asked about freet3 I was told he does not do that. I live in Nassau County, Long Island NY.
One more question...Is my current TSH 0.19L an improvement to TSH 0.05L? Is the higher number closer to "normal"? Is my current number borderline normal?
Since you are taking thyroid med, forget TSH.  As I explained above it is basically a useless test when already being treated for hypothyroidism.  Of course that is not what most doctors have been taught so they keep flogging TSH.  The  thing they should be concerned with is getting your med dosage high enough to relieve symptoms, which usually suppresses TSH, since you are taking your med  all at once., instead of the continuous low flow of natural thyroid hormone in the untreated state.    A good thyroid doctor will adjust your thyroid med dosage as needed to relieve hypo symptoms, without being influenced by resultant TSH.  
I was just thinking about something. My Vitamin D levels have been low for years(around 10) This past year I have been taking 2000IU D3 daily and my level is now 40. I have read D deficiency can raise TSH so is it possible that My TSH is so low now because of taking the D vitamin?
What other meds do you take besides thyroid?
Shae, no about the Vitamin D causing your low TSH.   Just read again my explanation about the dosing having such an effect on TSH.   More than just the dose itself.
Avatar universal
TSH is a useless test when taking thyroid med.   Medication dosage should be whatever is needed to relieve hypo symptoms, not TSH levels that make the doctor happy.    Our bodies are used to a continuous low flow of thyroid hormone (bothT4 and T3 ) from the thyroid gland, in the untreated state.  When you take your med dosage all at once in a short time, it spikes thyroid levels for a short time and suppresses TSH for the day.    This has been proved in several studies that I can link for you.  But before that please tell us about which, if any, of the following symptoms you have.  

Increased sensitivity to cold  (temp. below 98.6 which is considered normal)
Constipation  ( have to use fiber or laxatives)
Dry skin (have to use moisturizer)
Weight gain  
Puffy face    
Muscle weakness
Elevated blood cholesterol level
Muscle aches, tenderness and stiffness
Pain, stiffness or swelling in your joints
Heavier than normal or irregular menstrual periods
Thinning hair
Slowed heart rate
Impaired memory
Enlarged thyroid gland (goiter)
insomnia/sleep apnea

Also please post your thyroid related test results and  their reference ranges shown on the lab report.  If tested for Vitamin D, B12 and ferritin please post those also.
Helpful - 0
TSH 0.40-450...0.19L
T3total 76-181...92
T4Free 0.8-1.8...1.3
Vitamin D ..40
Positive ANA
I am tired,stressed,sensitive to temperature and light, hair loss, pain in joints(hands&thigh)
I have not been well for 20 years. I tried to get help but gave up. I think I figured out what I have. It is called Erythromelalgia.
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