Thyroid levels

[2124]

How come  my blood levels are reading lower when I have hashimotos and I have been taking synthroid for over 10 years. Tsh 3 came back at .18 low

[gimel]

Many doctors have the "Immaculate TSH Belief" that they were taught in Med School.  That belief assumes that TSH perfectly reflects the levels of the biologically active thyroid hormones, Free T3 and Free T4.  In actuality, TSH cannot be shown to correlate well with either Free T3 or Free T4, much less with symptoms, which are most important. The best correlation of TSH to Free T3 and Free T4 that I have yet to find is shown in Fig. 2 of this link.  As you can see and read, the correlation is poor.

http://nahypothyroidism.org/thyroid-and-aging-graph/

There are many sources that confirm that TSH is even less useful as a diagnostic after a patient is taking thyroid meds.  Here is one to start with.

http://nahypothyroidism.org/thyroid-hormone-transport/

Within this link, in the Treatment section, you will find reference to a scientific study done by fraser, et al.  

121. Fraser WD, Biggart EM, OReilly DJ, et al. Are biochemical tests of thyroid function of any value in monitoring patients receiving thyroxine replacement? The British Medical Journal 1986;293:808-810.

In this study you will find these conclusions.

Fraser et al investigated the correlation between tissue thyroid activity and serum blood tests (TSH, free T4 and T3) and published their results in the British Medical Journal. The study authors concluded that “The serum concentration of thyroid stimulation hormone is unsatisfactory as the thyrotrophs in the anterior pituitary are more sensitive to changes in the concentration of thyroxin in the circulation than other tissues, which rely more on triiodothyronine (T3).” They found a suppressed or undetectable TSH was not an indication or a reliable marker of over replacement or hyperthyroidism. They state,

    “It is clear that serum thyroid hormone and thyroid stimulating hormone concentrations cannot be used with any degree of confidence to classify patients as receiving satisfactory, insufficient, or excessive amounts of thyroxine replacement…The poor diagnostic sensitivity and high false positive rates associated with such measurements render them virtually useless in clinical practice…Further adjustments to the dose should be made according to the patient’s clinical response.” (121)


And finally for now, the best correlation of thyroid hormone tests to hypo symptoms is with Free T3, as can be seen in the referenced scientific study.  Free T4 and TSH did not correlate at all with the composite score of 8 subjectively rated major hypo symptoms.

http://www.ingentaconnect.com/content/routledg/cjne/2000/00000010/00000002/art00002

I think these links will be a great start.  If your doctor is still not convinced, let me know.  There's plenty more.

[lfb2166]

Where can I find journal articles on the when then tsh is lower than .02 &how some dont go hyper. My intergrative md is terrified of making me hyper and I keep telling her otherwise but she wanted facts. Where can I direct her. I think her practice would gain alot from this insight.

[gimel]

Frequently when hypo patients increase their thyroid meds enough to relieve symptoms, the TSH will become suppressed below the range.  That does not mean that you are hyperthyroid, unless you do have hyper symptoms, due to excessive levels of the biologically active thyroid hormones, which are Free T3 and Free T4.  For example, I have had a TSH of around .05 or lower for well over 25 years without ever having hyper symptoms.  There are other members with similar stories.

Were you tested for anything besides TSH?  If not you should always make sure they test you for Free T3 and Free T4 each time you go for tests.  Note that Free T3 and T4 are not the same as Total T3 and T4.  If you have been tested beyond TSH, please post results and reference ranges shown on the lab report.

What symptoms are you having, if any?


A good thyroid doctor will treat a hypo patient clinically by testing and adjusting Free T3 and T4 as necessary to relieve symptoms, without being constrained by resultant TSH levels.  Symptom relief should be all important not just test results.