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?"

[goolarra]

OMG, major groan..."most patients"...what about the rest of us?  Can you imagine what would be happening if diabetes were treated with the same principles?  This is depressing.

[gimel]

Here's an interesting bit from a study in the British Medical Journal.

"A question that remains to be answered convincingly is whether it
is clinically necessary to measure thyroid hormone concentrations in
patients receiving thyroxine replacement. The standard replace-
ment dose in Europe and America was 200-400 mcg a day until 1973,
when it was halved to 100-200 mcg a day on the basis of biochemical
measurements of thyroid hormone concentrations.   We are not
aware of any study that has shown that this reduction in the standard
dose has had any clinically beneficial effects. Different groups have
shown changes in sodium metabolism,'9 hepatic enzyme activity in
serum, and systolic ejection time intervals' in patients receiving
high doses of thyroxine, but such measurements have not been
shown to be of any relevance to patient care.


"We consider that biochemical tests of thyroid function are of
little, if any, value clinically in patients receiving thyroxine
replacement. Most patients are rendered euthyroid by a daily dose
of 100 or 150 mcg of thyroxine. Further adjustments to the dose
should be made according to the patient's clinical response. In our
laboratory 36% of all thyroid function tests are performed to
monitor thyroxine replacement. To stop doing these tests in such
patients would cause considerable saving in the costs of reagents in
laboratories using commercial kits."
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Unfortunately. from what we hear from the UK, they seem to have continued with testing, but predominantly only TSH, and they don't want to treat patients clinically (for symptoms).

[gimel]

Here is another interesting item.

21.9% of patients with Thyroid FunctionTests within the reference ranges were found to have inappropriately low TSH indices indicating pituitary dysfunction (Jostel 2009)

Not very encouraging for patients being diagnosed by TSH alone.

[gimel]

Here is more good info from the link I noted previously.




Kratsch 2005: Attempt to redefine Ref. Ranges with carefully screened population of healthy blood donors. No symptom questionnaires. 95% TSH range for the most carefully screened group: 0.04-3.77mIU/L,  95% free T4: 0.99--1.6 ng/dL, most labs report 0.7-1.7,  95% free T3: 2.6-4.4 pg/mL. Most labs 2.3-4.2)  Median Free T4 for males- 1.32 ng/dL. Median free T4 for females 1.2 ng/dL. Median free T3 for males 3.4 pg/ml, Median free T3 for females 3.1 pg/ml. Median TSH for males and females were 1.35 and 1.42. Notice that the free hormone ranges have higher lower limits. Many, many symptomatic “normals” have free T4 below 0.99! The upper range is lower than usual RR for free T4 but a bit higher for free T3. Question remains—On what basis can one claim that every person within the 2.5 to 97.5 percentile range is therefore “normal”? What if they are low in the range (say at the 5th percentile and are symptomatic?

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Note the significant differences between their findings on ref. ranges, compared to the ones we see every day.  I am not talking about the averages but the breadth of the ranges.

[HessyKat]

Bless you gimel in your endeavor to bring some kind of awareness with these thyroid issues. I wish you much luck with the Surgeon Generals office. I have been so frustrated with the thyroid treatment for years. I was dx. with Graves and Hashimotos at the age of 21yrs old and I still battle to find some kind of relief from my symptoms. Here I am 48yrs old now and it has been a long journey.

[LazyMoose]

1)Power in numbers has proven to be the ONLY way for any change in this country, the power of true representation - its true, think about it. Individuals mean nothing.

2)Like gimel said, who do we aim our campaign at? There is not one obstacle, many, and widespread.

3)I think the other forums need to be on track to, they all must have some small hand full that are 'doers'.

4)I don't think this type of post should just disappear, it needs to be on top with the 'welcome wagon' for others to take note. This post was about TSH / Frees,........ the subject has changed. We had several posts on thyroid awareness. We need one on a thyroid treatment campaign. - exactly to the point. Just being aware does not mean proper treatment / Dx'ing.

The new 'Thyroid Coalition', was supposed to be a representation of all of us for these purposes as I understood. So far its just a very nontechnical face book thyroid page that provides less information than this forum, seems to be more about emotional support with thyroid disease. Currently its a disappointment, as we don't gain any ground from another forum. Maybe it will change? I hope so.

We do need to attempt to change thyroid treatment on a National level. A talk show always stirs things up. But who would represent us there? And magazines, it might be a liability thing with them - they want Drs in there stories, not what some patient thinks - I understand their view.

Surgeon General - good idea!