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Many doctors seem to regard the diagnosis and treatment of hypothyroidism as a relatively simple matter – just run a blood test and if the results lie below the bottom of the reference range, administer just enough thyroxine to bring them back above.
Those of you who have long felt unwell, suspecting that your thyroid is the cause of your symptoms but repeatedly being told that your blood tests are normal, may by now be thinking rather differently. If this is the case, you will not be surprised to learn that thyroidology is littered with mythology! This, the first of a series of articles challenging that mythology, explodes TSH as the 'golden measure' of thyroid health, blood tests as the only reliable way of diagnosing thyroid disease, and precision in thyroid medication.
Dr Anthony Toft has spoken of the "exquisite sensitivity" of the TSH measurement, meaning that a small increase in T4 is accompanied by a relatively large decrease in TSH, and visa versa. You might be thinking that this sounds perfectly reasonable. Okay, let's take a closer look.
TSH is produced by the pituitary gland, special cells at the back of which sense the levels of T3 and T4 in the blood. It also receives information from the hypothalamus, and other parts of the brain, representing your emotional state, what demands are being made on your body, how warm or cold you are, where in the diurnal cycle you are, and so on. The pituitary then has to work out from all this information what the blood levels of T3 and T4 should be, compare them to what they actually are, and adjust the production of TSH so that your thyroid gland decreases or increases its production of thyroid hormone appropriately. If there is something wrong with your pituitary gland, hypothalamus, or the information coming into your hypothalamus, the measurement of the TSH level in the blood can no longer be quite such an accurate, sensitive or reliable indicator of the health of your thyroid as generally supposed.
Furthermore, a TSH measurement won't tell you if:
you are converting enough T4 into T3, or
you are converting too much T4 into reverse T3, or
your thyroid is being attacked by antibodies, or
you have T3 receptor resistance, or
you are suffering from adrenal insufficiency, or
you are deficient in those minerals and vitamins essential for good thyroid health.
It is commonly assumed that limiting your dose of thyroid hormone to that which normalises the TSH level in your blood, returning it to about the middle of the reference range, will restore you to normal health. Dr John Lowe has searched in vain for scientific evidence proving that imposing a TSH normalising dose of thyroid hormone really does result in normal thyroid hormone levels in the cells - which is what really matters - and concluded that this is merely a scientifically unproven assumption made by endocrinologists. In fact, John Lowe's next book is to be entitled 'The Tyranny of TSH'.
A full picture of your thyroid health cannot be obtained by checking only your TSH level any more than the health of a business can be obtained by looking only at the bank balance. Whilst an 'abnormal' TSH level may sometimes provide some idea of your thyroid health - this is a bit like trying to decide when a stopped clock is telling the correct time - it will not pin-point where the problem is. Finally, it is interesting to note that the ELN Laboratories point out, in the information sheet that accompanies their Urine Test Kits, that "TSH is grossly in feedback with serum T4 only, not so much with serum T3, while the patient's well being depends on the free T3 that is disposable inside the cells."
Whilst a full thyroid screen blood test is certainly an improvement on a TSH check alone, it is fallible and can produce false negatives. To put things in perspective, doctors have been looking for a diagnostic test for thyroid problems ever since the importance of thyroid hormones was recognised late in the eighteenth century. In his book, The Great Thyroid Scandal, Dr Barry Peatfield points out that there have been "about 40 different tests for thyroid illness because not one has been found to be reliable". Unfortunately the currently used thyroid function test based on a blood sample is not much better than any of its predecessors.
The problem is that what really needs to be measured is the thyroid hormone level in each and every cell of the body. As this can't be done, thyroid hormone levels in the cells have to be inferred from those in the blood stream. For this to work, there must be a fully understood and consistent relationship between the levels in the blood stream and those in the cells. Moreover, the relationship being used may only hold good under certain conditions and these conditions must be properly understood as well.
For example you can now buy electronic 'weather stations' that monitor atmospheric pressure, infer from it what the weather is going to be and select the most appropriate of five animated pictures - sunny, sunny intervals, cloudy, rainy or stormy - for display. Now, inferring rain from low pressure is fine because it can rain at any time of day or night. On the other hand, inferring sunshine from high pressure is a bit dodgier because the sun can only shine during daylight hours! Of course, all we have to do to check the prediction of sunshine is to look out of the window to see if it is still daytime or not, but can we do a similar thing for the thyroid function blood test results?
When inferring the levels of thyroid hormone in the cells from those in the blood stream, one underlying assumption is that there are no problems with their transfer from the blood stream to the required point within each cell in your body. However, if your thyroid has been under-producing for a long time, the receptors on the outside of those cells may for various reasons close down with the result that the consumption of the hormones is reduced even more than the production of them was. The unused hormones will accumulate in the blood stream where the levels will eventually return to within the 'normal' range. If a blood sample is now taken the levels in your blood stream will register as normal, but since those in your cells will be low the blood test results will not line up with the clinical picture. Since the blood test is generally regarded as the most reliable way of diagnosing thyroid conditions your hypothyroidism will probably go undiagnosed.
There are many other problems with thyroid function blood tests, including the interpretation of them. The use of 'reference limits' seems to encourage the recognition only of fairly extreme under or over activity of the thyroid gland as if lesser deviations from 'normal' don't make people feel unwell. The reference limits themselves may be too broad if they were based on a sample of 'healthy individuals' too many of which had mild but unrecognised hypo or hyperthyroidism. Now, if doctors have come to rely solely on the blood test to detect these conditions and have therefore lost their own diagnostic skills in this area, how can anybody be sure that this has not happened? The real myth here is that the blood tests are reliable at all.
Fortunately thyroid disease can also be diagnosed from 24 hour urine tests, Barnes basal temperature checks, clinical signs and symptoms, and the clinical history - although a thorough investigation of the clinical history will not be possible in a typical 10 minute session with your NHS GP. It should also be said that, like the TSH test, the Barnes basal temperature test cannot pin-point where the problem is.
Endocrinologists seem to have the idea that the treatment of hypothyroidism can these days be carried out with great precision. This is presumably based on the assumptions that:
you can measure the levels of thyroid hormones in the blood very accurately,
the potency of each tablet never varies,
you can find a combination of tablet strengths that make up the precise dose your doctor thinks you need without you having to sub-divide any tablets for yourself, and
your thyroid hormone needs never change.
It is probably true that thyroid hormone assay techniques can theoretically produce very accurate measurements. However, no measurement can ever be made which does not have some degree of uncertainty or imprecision. As the concentrations of thyroid hormone in the blood stream are extremely, small their measurement is actually quite difficult. Furthermore, there are several different versions of the radio-immunoassay measurement technique in use, each having its own reference range. Even two labs in the same city may be using different ones. Now, the measurements made by all the pathology labs throughout the UK are periodically checked using standard solutions supplied by the regulatory authority. Apparently, when all the results are compared they are usually found to vary by up to one quarter of the reference range in either direction (this doesn't sound quite so precise any more, does it?).
The potency of the tablets should not vary from batch to batch provided they are produced by a reputable manufacturer who regularly checks the strength of the tablets he makes.
Most medications are available in a range of different strengths and it is possible to combine tablets of different strength to achieve different dosages. It is unlikely though that that the precise dose needed can be obtained without having to divide a tablet - can you halve a tablet exactly? Imprecision will be introduced by the doctor when he prescribes the combination of tablet strengths nearest to the dose he thinks you need.
However, your needs do change with time. If you were hypothyroid for a long time before being diagnosed you will probably have slowed down a lot since you lacked the energy to do otherwise. When you first start your thyroid hormone replacement therapy you will no doubt be fairly inactive. As you pick up you will start to become more active and will need a higher dose to meet your increasing needs. If you then take a holiday somewhere very warm, you will need to reduce your dose because your body will not need to create so much warmth for itself.
So, as the right dose of thyroid hormone for you is the one at which you feel your health is optimum, and that dose can vary according to how active you are or how warm it is, it is not possible, surely, to specify a precise dose of thyroid hormone exactly meeting your needs for evermore.
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I have discussed the myths of TSH as the 'Golden Measure' of Thyroid Health, blood tests as the only reliable way of diagnosing Thyroid Disease, and precision in thyroid medication. I look forward to dealing with some more myths in the near future.
© Peter Warmingham
Many Doctors seem to regard the diagnosis and treatment of Hypothyroidism as being a relatively straight forward matter. As I said in Part 1 of this article, those of you who have long felt unwell, suspecting that your thyroid is the cause of your symptoms, and who have been repeatedly told that their blood tests are normal, will by now be thinking rather differently. If this is the case, you won't need me to remind you that the field of thyroidology is littered with mythology! This is the second of a series of articles designed to challenge those myths. In this article, I am going to talk about the myths of Thyroxine being the only thyroid medication, normality, autoimmune antibodies being harmless, and a suppressed TSH causing Osteoporosis. As I write, I am realising that many of the myths I am talking about overlap with one another, and that we actually have an interacting network of myths to deal with!
Thyroxine is the first and only choice thyroid medication for doctors who don't, apparently, know any better (most of them, it would often seem). Many doctors think, incorrectly, that they may not prescribe anything else. Now some people do get better on Thyroxine, but other doctors, like Dr John Lowe, maintain that most don't and for them there are alternatives, fortunately, most notably Armour Thyroid.
The problem with Thyroxine is that it is a synthetic version of the thyroid hormone T4. Desiccated porcine thyroid was the medication first made available to hypothyroid people and it is a natural substance. I don't want to use the term 'drug' in this context because for me, drugs are substances designed to change or enhance the way you feel whereas replacement thyroid hormones are taken to help you restore the way you feel! Unfortunately, before thyroxine was introduced, no clinical trials were ever carried out to determine how effective it was in comparison with desiccated porcine thyroid extract. Now we are in the age of evidence-based medicine, some doctors might argue that there is no evidence to say that Armour is better then thyroxine.
One of several reasons why people may not respond well to thyroxine is that they are unable to convert enough T4 into T3. If you give T4 to these people all that happens is that the T4 builds up in the blood stream to toxic levels whilst their tissues remain woefully short of T3. In such cases, a much better response may well be obtained by taking T3 instead of T4. This will fundamentally affect the blood test results, causing the T4 and TSH levels to fall dramatically but as the tissues need T3 to work properly, so what? In fact, your own thyroid needs enough T3 to work properly so when it gets more T3 it will eventually start to work better as indicated by a recovery of the serum T4 levels even though no T4 is being taken by mouth
Another reason why people may not respond to thyroxine, or to Armour Thyroid for that matter, is that they have also developed adrenal insufficiency and the adrenal hormones are needed both to open the T3 receptors in the cells and to facilitate the T4 to T3 conversion. These people need also to take hydrocortisone, prednisolone or adrenal glandulars to provide the required adrenal support. Others may also need to take 7 Keto DHEA.
If you are unable to obtain thyroxine or Armour Thyroid for any reason, you can of course take thyroid and adrenal glandulars to support your thyroid and adrenals. Furthermore, if you have a deficiency in any of the vitamins and minerals necessary for thyroid health, you may need to supplement those as well.
I think I have shown that with only a little thought it soon becomes apparent that there are quite a number of ways of treating hypothyroidism, and that it is quite wrong to think of thyroxine as the only medication that might be needed.
We go to our doctor with symptoms and have a blood test, but the results come back 'Normal'. What exactly is meant by 'Normal?
In the case of the blood test, it means that the results are in the normal range – but normal for whom? The normal range is actually determined by measuring the blood serum thyroid hormone levels in members of a group of healthy, symptom free people and looking for the lowest and highest readings that between them contain 95% of the sample group. That means that 5% of those healthy, symptom free people have been arbitrarily declared abnormal and they would be eligible for treatment of their absent symptoms!
Of course, for that group of healthy individuals, it is normal for them to be symptom free and able to do anything they like, whenever they like. On the other hand, for those of you who are not healthy it is normal for you to have symptoms and to be restricted in what you do.
So, is it normal to do hours of physical training every day? Not for most people but it is for people who want to win Olympic medals. Is it normal for people to live in houses made of blocks of ice? Not for most people but it is for Eskimos. Is it normal to fly at an altitude of 10,000 feet every day? Not for most of us but it is for airline pilots. Is it normal to hold your breath underwater for twenty minutes or longer? Not for most of us, but there some who train for attempts to break records for doing just that. Is it normal to live in constant pain? Again, not for most people but it is for some unfortunate individuals.
The point is that there is no absolute, definitive 'normal' that can be applied to everybody. Each of us might be 'normal' in some ways and yet be abnormal in lots of other ways because in the final analysis we are all individuals, after all.
So, when the doctor says your blood tests are normal, he means that they fall within the 'normal' or 'reference' range, as it should be called. The problem is that he can't possibly know what is 'normal' for you as an individual and that is a vital piece of information he is missing. You may well have a working range of your own that is much narrower than the doctor's reference range as most people in the sample group probably did.
Patients are frequently told by their medical practitioners that their thyroid antibodies are not harming them. However, the most common cause of hypothyroidism is, as you probably already know, Hashimoto's disease. Now, in Hashimoto's disease thyroid auto-immune antibodies attack and destroy the thyroid hormone producing cells in your thyroid gland. Such attacks may initially stimulate the thyroid into over activity but the auto immune antibodies gradually turn the thyroid into scar tissue, destroying in the process its ability to produce thyroid hormones. I'm not sure exactly what triggers all this off but it comes to mind that since cortisol, one of the adrenal hormones, actually moderates the immune system, one predisposing factor in this might perhaps be the presence of adrenal insufficiency.
In reality you should not have any autoimmune antibodies in your body at all although of course you do need normal antibodies to provide you with vital resistance to infectious diseases, etc. If you do have autoimmune antibodies, you can be sure that they will be doing you no good. Furthermore, if you have one type of autoimmune antibody active in your body, you may well have others to go with them, and they won't be doing you any good either.
In practice, because thyroid antibodies levels tend to wax to wane, they may not always show up as being abnormally high in a blood test – the trick is to catch them when they are high! In Dr Bo Wikland's clinic in Sweden thyroid problems are routinely investigated using the Fine Needle Aspiration (FNA) technique. Dr Wikland's experience, as published in The Lancet (2001 and 2003), is that FNA is actually very valuable in the demonstration of thyroid autoimmunity; superior in fact to antibody testing. It is interesting to note that Dr Wikland has noticed that when the TSH level is suppressed, thyroid antibodies will be suppressed also, so here is a further argument against TSH as the golden measure of thyroid health (discussed in the first 'Myths' article).
Finally, let's remember what happened to the unlucky six of those eight volunteers who recently took part in the disastrous 'elephant man' trial - they were all given a drug that stimulated a very powerful autoimmune reaction.
Bones are living entities as are muscles and ligaments. If you don't use your muscles they will waste away. On the other hand, you can deliberately build your muscles up through exercise. Bones similarly respond to the demands made of them.
If you are feeling generally listless due to being hypothyroid, you are not going to be terribly active physically and so won't be making very great demands on your bones. This will in time lead to a reduction in bone density as happens to Astronauts when they spend many weeks is space stations orbiting the earth in weightless conditions. In fact, Astronauts have restrictions placed upon them as to how long they can remain in a weightless condition in space for this very reason.
The idea that suppressed TSH is associated with osteoporosis comes from a number of studies carried out by various researchers. Because these gave conflicting results a further study, Long-term Thyroxine Treatment and Bone Mineral Density was carried out by J.A. Franklin, J. Betteridge, J. Daykin, R. Holder, G.D. Oates, J.V. Parle, J. Lilley, D.A. Heath, M.C. Sheppard and published in the Lancet in 1992. The synopsis reads,
"Studies of the effect of thyroxine replacement therapy on bone mineral density have given conflicting results; the reductions in bone mass reported by some have prompted recommendations that prescribed doses of thyroxine should be reduced. We have examined the effect of long-term thyroxine treatment in a large homogeneous group of patients; all had undergone thyroidectomy for differentiated thyroid cancer but had no history of other thyroid disorders.
The 49 patients were matched with controls for age, sex, menopausal status, body mass index, smoking history, and calcium intake score; in all subjects bone mineral density at several femoral and vertebral sites was measured by dual-energy X-ray absorptiometry. Despite long-term thyroxine therapy (mean duration 7-9 [range 1-19] years) at doses (mean 191 [SD 50] þg/day) that resulted in higher serum thyroxine and lower serum thyrotropin concentrations than in the controls, the patients showed no evidence of lower bone mineral density than the controls at any site. Nor was bone mineral density correlated with dose, duration of therapy, or cumulative intake, or with tests of thyroid function. There was a decrease in bone density with age in both groups.
We suggest that thyroxine alone does not have a significant effect on bone mineral density and hence on risk of osteoporotic fractures."
You will note that this study was carried out on groups of patients who had undergone thyroidectomies for thyroid cancer and did not have any previous history of thyroid disease. They would therefore have gone straight onto the routinely prescribed dose of thyroxine after having their thyroidectomies. T3 and T4 are after all hormones the body should be making for itself so it is hard to imagine why taking replacement doses of them by mouth should have dire side effects such as osteoporosis. If you were taking too much thyroid hormone, the ensuing symptoms of hyperactivity would prompt you to reduce your dose. Conversely, if you weren't taking enough you would feel unwell anyway and would increase your dose until you did feel well. When you are taking the right amount to actually feel well again your TSH will be suppressed because you have taken control of your thyroid hormone input away from your pituitary.
When a dosage of thyroid hormone is imposed that merely returns the blood TSH levels to 'normal', most patients will not feel well enough to go out and run marathons. In fact, most people don't actually feel better until they are on a dose of thyroid hormone that actually suppresses their TSH levels.
My conclusion is that you are more likely to develop weak bones when you are still suffering from fatigue and all the other symptoms of hypothyroidism because your blood TSH level is not suppressed, and consequently are abnormally inactive for a long time.
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In this article, part 2 of 'Myths', I have discussed thyroxine as the only thyroid medication needed, 'Normality', autoimmune antibodies being harmless, and a suppressed TSH causing osteoporosis. I look forward to dealing with yet more myths in the near future.
© Peter Warmingham