What is the value of TSH Test vs. FT3/FT4

[gimel]

Super Sally and I have had discussions about the usefulness of the TSH test and whether it should continue to be part of diagnosis and treatment of hypo patients.  For background I have copied our posts below.  I'd like to invite members to freely provide their opinions and experiences relating to these three tests.  I'd also like to invite members to provide links to any scientific data they have seen that either supports or questions the utility of TSH, or FT3, or FT4.
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by Super_sally888
, Nov 29, 2010 07:14AM
Hello,

the correct dose of thyroid is different from person to person.

It sounds that 25 mcg is too low.

I don't know if 75 mcg is suitable.  To tell, you need to take that dose consistently for at least 4 - 6 weeks and then test TSH, FT3, and FT4.

TSH should be in the range of 1 - 2, and FT3 and FT4 should be about middle of the reference range, or a little higher.  Meds need to be adjusted (usually by adding 25 mcg/day, or sometimes 25 mcg additional every second day).

A TSH of 7.0 is still too high.  If you've been taking the 75 mcg for at least 4 weeks at that dose, then you may need an increase to 100 mcg.

Changes can only be made about every 6 weeks, because this is how long it takes for levels to stabilise after each change.

HOpe this helps.

by gimel
, 10 hours ago
To: Super_sally888
I don't really understand giving  a target range for TSH, freeT3 and freeT4.  Isn't the real target the relief of symptoms, which has to be accomplished by adjusting levels of the biologically active thyroid hormones,  free T3 and free T4?  

Yes, it is true that symptom relief frequently requires that FT3 and FT4 are adjusted into the middle of the range or higher;  however, since TSH is directly dependent on feedback to the thyroid glands from the hypothalamus/pituitary, which data that I have seen shows that TSH is affected mainly by FT4, then you cannot adjust FT4 and TSH independently.   So a separate target level for TSH may possibly be confusing to a new member.   In fact, once a patient is taking thyroid meds based on testing and adjusting levels of FT3 and FT4, in most cases, I'm not convinced of the utility of a repeat TSH test.  It probably causes more problems than it solves.

In fact, when I look at TSH data like shown in fig. 2 of this link, I have a hard time finding any enthusiasm for TSH testing at all.  LOL  I think we'd all be far better off being treated clinically and by testing for FT3 and FT4.  

http://optics.merck.de/servlet/PB/show/1809250/Thyroid-Inter-3-2008.pdf

Super_sally888
, 8 hours ago
To: Gimel
Hi,

I certainly agree that patient's meds should be adjusted based on symptoms.

I also think that target blood ranges are also very useful as a starting point for people like rajbir687 who are learning about thyroid and how it should be managed.

Getting numbers to within the ranges stated (with priority given to FT3 and FT4 levels) is a good starting point and things can be tweaked from there.  It won't work for everyone, but it will work for the majority.

Let's face it, most doctors still treat based on TSH alone.  So, at least don't go against these doctors - but instead encourage more comprehensive testing, particularly in cases where the symptoms don't match the bloodwork.  We want to encourage people coming to this forum to work with their doctors.

I am one whose bloodwork on TSH is far from that target - it is very low even while FT3 and FT4.  Honestly, even Dr. Lupo on his expert forum repeatedly says that TSH should be used to guide treatment - he doesn't seem to pay much attention to FT3 and FT4 as long as they are anywhere in or close to the range. Given this,  I am constantly questioning myself about this.  Particularly as I may have bone loss.  Should I dramatically reduce my meds and try to get the TSH up?  I am trying to have another baby now, so not time to play - but will have to play later.
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I'd like to start the discussion by pointing out the data in the link referenced above and ask "How can anyone possibly have any confidence in TSH as a diagnostic when there is this much data scatter, among patients with no known thyroid issues?"

[LazyMoose]

Barb, In your case your known 'target' is also the frees.

Since you can adjust these individually , do you feel FT3 in upper range is more responsive to eliminating symptoms compared to FT4?

Have you ever had FT4 in the low end on range, but FT3 upper third and still felt great?

[redheadaussie]

Maybe I am just different, then again as my Endo has stated, I am Unique! I have pretty much been at the mid range for FT3 alot of the time, only in the past 18 months or so have they really started to fall.  My FT4 has usually been in the upper 3rd range.  I always feel totally crud.
If my TSH is off I feel crud. I can get the symptoms of hyper and know that my FT3 is still falling and my TSH can be for example, 0.06. If my hypo symptoms come along, I can know that my TSH will be up there and any thing over 1.0 is a killer for me.

Personally I know full well that if I were treated by just looking at my FT3 and FT4 I would be dead. If you care to see my photos and my pathology results for 3 years, I go all over the place. If you were a doctor here in Australia, and treating me just by the free's (which they don't anyway, ha ha!) you would say I was just a tad over or under but still just within range, so no need for medication! BUT looking at my TSH, which they do look at only, I am dosed according to that number.  So in a back to front way, I am glad they look at the TSHas their main concern. Of course, I would dearly LOVE for them to look at the bigger picture of all 3 tests, but they don't.

TSH being a pituitary hormone to thyroid trigger hormone is still a very important tool to use in the bigger picture, in my opinion. Without knowing how much stimulation is being sent to the thyroid which in turn triggers the T4 production,  how can we be aware of how the feedback loop is working?

When the TSH is released it goes to the thyroid to tell it to make some T4. If that is off then the thyroid's response to producing T4 is not going to be optimal, and therefore the T3 is not going to be great either.  So it is very important to use all of them together to see the bigger picture.

Dismissing the TSH totally is like saying you can run a car without petrol. Without it there is no going anywhere! Same as the thyroid, without that hypothalamus releasing TRH to the pituitary to release TSH the whole shebang would fall over.

Yes the T4 is important too. This tells us our thyroids are producing what they should be. For those of us without thyroids this allows us to see if our medication is actually at the level it should be so that the production of T3 can be made in our bodies. (Not all of the conversion happens in the thyroid, contrary to popular belief)

One of the main issues still contested is the fact that those rotten reference ranges are an averaged mean of a small number of the population. This mathematical formula is a generalisation, which should not be used for individuals. It was meant to be a guide as to where most people ought to be in the so called normal range if not being treated or having any thyroid disease in the first place. Obviously those studies are flawed in saying that Mrs Jones who has a FT4 say of 18  which is mid-range in Australia is perfectly normal, when she feels lousy, hyper and totally miserable. Her doctor says 'No problems here,  your thyroid is producing within the normal levels of others in society. Off you go'. But her TSH is say at 0.05 which is out of range in Australia and she would be treated. YET if her TSH was say, 0.40 and she was still complaining of the same symptoms at this imaginary same visit, her doctor more than likely would say, "Well you are just above the lower range, but still in the normal for society, so off you go." (0.35 being the lower range here in Aus)

So in that case, just looking at her FT4 on it's own is useless.  To be continuesd!!
  

[LazyMoose]

Interesting. I would be sick if I aimed for a target TSH. I can see its usefulness as a very general guide for detection, but even then its not accurate. This may differ as world TSH ranges differ.

You are able to treat and know your target range based on TSH possibly if you have been on one brand of med for years. A 'target' or 'sweet' TSH value will change from med brand to med brand in one person, I unintentionally proved this. So TSH is not a constant or reliable value for fine tuning.

An interesting fact I would like to point out in my experience of using 6 brands in 2 - 2-1/2 years. The common denominator of lab values from these brands when ever I felt good was free levels, not TSH.

***My point in my case is that my target TSH to feel good on these 6 different brands varied, never the same. The free levels and maybe the ratio of t3/t4 for me to feel good was not very different.***

Info above is about the closest to a scientific 'test' I have read on this forum. (LOL) But I have only been here under 2 years.

My 'feelgood' TSH value varied because the correlation of TSH to Frees varied brand to brand.  The common denominator lab value which corresponded to my feeling well was specifically a certain upper third Free T3 range within the range - along with FT4 somewhere in range.

[LazyMoose]

In my case, I was sickly hypo for 10 years while being treated and tested solely by TSH, and the old US range.

Ten years wasted. Thats what led me to this forum.

[redheadaussie]

..continued..Sorry guys we had a major thunder and lightning and heavy dump of rain, so had to put the computer to nigh nighs.

For me, not being able to get any other type of T4 medication other than Eutroxsig in Australia (Oroxine being the generic and identical product) makes it difficult to be able to note any variance in the whole TSH, FT4 etc trip. Yes, it does lead to consistency in results though.

I often see the Americans who post say they feel better on such and such a brand. There tends to be a consensus on that by others who all seem to do better on Brand X instead of Brand A. It would be very interesting, and my engineering friend came up with this idea, of having everyone do as I did, make a type of spreadsheet with Date started medication, the date of blood draw, the TSH etc and the ref ranges. It would be great to be able to put all that in some kind of database and then see what results are noted and at what point most people find they feel the best. I bet it is nothing like the so-called reference range tell us to be!

I wasn't saying that I am aiming for a sweet spot TSH, rather that I feel better at a certain level than at others!BUT only if my Frees are in any sort of normal range, which 80% of the time they are not. As I said earlier I am a bit different to the usual cases and this is still an ongoing battle for me to find anyone who can explain why I go hyper on low doses and hypo on higher.  For me if I was treated just on my Free's I would have a heck of a time living for very long.

The Free T4 shows that the body is producing pro-hormone and the Free T3 shows it is being utilised. How well that system is working is a highly individual thing, and that is where the reference ranges are often useless. I have been fighting this illness for over 20 years now, and I am tired of being told my levels are just over or just under and nothing to worry about. I have symptoms, dear doctor, not numbers, and I would like to feel better.

I was never treated solely by TSH even though it was obvious something was wrong. Our doctors here would even refuse testing for that. Unless you walked in with a raging goitre, it was never 'allowed' unless 'clinically suspicious' for testing. I had only 3 thyroid tests done in near 10 years and even then I had to cry (literally) to get them and when I got the results it was only TSH anyway!  Which was only 'just' slightly above the lowest range!  Even if they had just treated me by TSH alone with all my raging hyper symptoms at the time, I would not have lost my kids, my home, my job, my relationships. 20 years later I am still fighting the stupid mentality of ref ranges mean you are ok.

20 years of my life wasted, and still wasting. Gah!

[Super_sally888]

Hi Everyone,

For the sake of discussion, here's my beliefs from much reading, person, and many years observation on this forum:-

1. TSH should always make reference to the 'updated ranges' of normal being in approx. range of 0.5 - 2.5.

2. TSH is a good general screening tool for people who are not on any thyroid medication at all.  I even believe it is of itself adequate in the 'non-symptomatic' population for screening purposes.

3. However, the key word here is 'non-symptomatic' population.  If someone comes to the doctor, has every symptom in the book (for hypo or hyper), then a full thyroid panel should always be done.

4. For people who are symptomatic, FT3 and FT4 should always take priority over TSH.  Thyroid issues should not be ruled out in 'symptomatic' people unless FT3/FT4 are close to mid range.

5.  I believe that a high TSH should nearly always be treated as meaning hypothyroid.  However, a very low TSH does not necessarily mean hyperthyroid, unless the levels of FT3/FT4 and the symptoms clearly show that.

6. Some people it seems do fine using TSH to monitor their thyroid levels and adjust meds.  I think this is ok so long as they feel good and have no symptoms.  Annual checks of levels is also fine once they are stable, providing there are no symptoms / they feel good.  

7. However, for people who have been on thyroid meds for any length of time TSH can become inadequate for monitoring.  IN these people their levels should be monitored on basis of FT3 / FT4 targeting levels at least mid-range as a starting point, and then tweaked from there to a level (within the range - for what that range is worth) but where they feel good and no symptoms.

8. I also believe that T4 only meds are overused and that many people will feel better on a properly dosed T3/T4 combo or a dessicated thyroid product.  

9.  Initial adjustments of meds when just starting thyroid meds can use TSH for gross adjustments, but finetuning must then be done based on how the patient feels, and finally using Ft3/Ft4.  The ranges are pretty broad and it is important to find out where an individual feels best.

10. Thyroid is not a condition where patients can just trust their doctor to prescribe a drug and they will be well (nothing like taking an antibiotic for a bug).  It is a long-term condition where the patient and doctor must work in partnership.

11. There are non-thyroid conditions that can be mistaken for and/or exacerbate thyroid conditions.  These include anaemia (low iron / low B12, vitamin D deficiency, PCOS, among others.  These should be screened for an treated appropriately, as part of thyroid management.

In Summary:-

There is no one size fits all.  

Realistically and cost-effectively, the minimum tests to get get the most reliable results should be used.  How a patient feels is at least as important, but often more important than blood work results. Symptoms and blood results should be used together.  

TSH is a useful tool, but it is the least important in long term and symptomatic thyroid patients.

I think there can be testing / symptom algorithims / flow charts to guide treatment.  This flow chart would rely both on blood levels and symptoms.  It would also consider some alternatives for checking if thyroid levels were apparently ok, but the patient still had symptoms in the face of apparently ok blood work.

I think we all actually agree, but there are shades on that agreement and slightly different emphases between us all.