CONTROVERSIAL THYROID MEDICINE - DIAGNOSIS OF SUBCLINICAL HYPOTHYROIDISMThat's a mouthful of thyroid medicine, and it doesn't get any easier. To be fair, it has got a lot easier over the course of my professional lifetime, but there is still a long way to go. When all else fails, I frequently resort to the "suck it and see" approach of a trial of thyroid replacement therapy - details later.
Symptoms of thyroid problems - underactive thyroidThe boiled frog principle is an unpleasant analogy, but does drive home a point.The story goes that if one puts a frog into boiling water it dies very unhappily and maybe noisily - but certainly with a lot of kicking. If one put the frog into nice cool water and gradually heat it up to boiling, the poor frog dies without so much commotion. The heat crept up on it. I haven't tried to confirm this. Symptoms of low thyroid creep up on one - you never see them coming. Thyroid medicine is sneaky. Aches and pains are part of the story. A good list of other symptoms is on the
thyroid institute.org site
Thyroid test results, in under active thyroidTSH levels are commonly used. Thyroid stimulating hormone or thyrotrophin, is the pituitary derived hormone accelerator for our thyroid gland.This is increased if the thyroid is having trouble doing its job, to give it a kick in the pants. There are a number of problems with this test. The commonly accepted reference range of 0.5 to 4 is in dispute, and the test depends on having intact feedback control mechanisms. Our brain measures the ambient temperature, the current blood levels of thyroid hormones and responds to other hormone and interleukin chemical messengers - lots of things can influence TSH. Gut derived bacterial endotoxin binds to TSH receptors in our thyroid gland, blocking its effect - so the output from the gland no longer reflects only the TSH level.
Reference ranges for blood tests1 in thyroid medicineThis is the range of values assuming that one is just as likely to have above as below average levels, encompassing 95% of a healthy population's results.Most people have results close to the average, and the further from here, the fewer results. This produces the "bell curve" distribution. One problem is getting a truly healthy population to give one this reference range. Remember that boiled frog principle. It has been pointed out that if people with a family history of thyroid disease and those with anti thyroid antibodies in their blood are excluded, the reference range becomes 0.5 to 2.5! The other problem is the wide range of normal variation, even more so for T4 levels. If someone has a level bang in the middle of the reference range, we are happier - but for all we know they may have been previously at one extreme of the range, and healthier for it. TSH (accelerator) levels high in the reference range plus T4 (output) levels low in their respective range, is getting suspicious.
have you had previous tests of your thyroid?If you know or suspect that you have, make every effort to obtain the results.Comparing current with previous results is very valuable. The position in the reference range should remain the same in health. If it has shifted a lot, a "normal" result may be shown to be quite the reverse. If you have a thyroid test now, ensure you get a copy of the result, as you may shift or change doctors in the future.
Therapeutic trials in thyroid medicineThis is the suck it and see method, which I believe should be more widely used.Gelb advocated checking serum cholesterol and basal metabolic rate before and after a trial of thyroid hormone replacement. These fell and rose respectively, when a person had been hypothyroid. My method is to take triiodothyronine 20 mcg. tablets over three or four days, using symptoms as the guide. This is much quicker, but does have placebo response as a confounder. We keep a bottle of these tablets and people take half a dozen for the test. There are some circumstances where this sort of test is inappropriate, such as in people with angina or heart failure. It has to be prescribed and supervised by your doctor. If your doctor is happy to contact me I'll be very happy to discuss it with them. On day 1, take one tablet in the morning.At the end of the day, take stock of how you have felt.Three possibilities are better, worse or no different. Better might be more energy, an easier bowel action, not so cold or getting rid of a large amount of fluid (as urine.) Pain might not sound better, but ones aches may be worse. Aches and pains in hypothyroidism, commonly get worse when thyroid replacement is first started. The test is now complete, but you can use up remaining tablets at the dose of one per day. Worse in this context is like a "cat on a hot tin roof." One might feel jittery and shaky, nervy and frightened or feel palpitations. The tablet will wear off, so just rest and wait. Dispose of the remaining tablets safely. The same means tomorrow take one in the morning and one at midday, then observe oneself as before. If you are sure there is no effect whatsoever, increase to three and even four tablets, on successive days, until some positive or negative effect is felt.
Wilsons temperature syndromeThis chap's ideas have come in for a lot of criticism, but I have a couple of patients who have fitted his description and responded exactly as he predicts.The proposition is that we can be stuck producing inactive reverse T3 rather that active T3, and just need a little help to get back on track. Advances in thyroid medicine can come from sources outside of conventional endocrinology.
The ultimate test of thyroid functionResting metabolic rate is probably the best, as this is an end result of thyroid hormone action.Brachioradialis reflex timing is apparently well correlated with this.
Should one be replacing thyroid hormone at all?Sam Queen from the institute for health realities is concerned about this. He always wants to know why the body is running along with reduced thyroid function, in order to treat the underlying problem.I am sure that he is correct in this concern. Thyroid medicine needs to be tackled holistically. Treating thyroid with replacement is just like any suppression of symptoms. The underlying cause is not corrected, and in fact the body may have been better off with the reduced thyroid function. This applies to borderline and very mild hypothyroidism, not severe. Thyroid medicine may reflect disturbances in other areas of medicine.
Taking kelp tablets?The drug amiodorone, iodine containing contrast media used in radiology and kelp tablets, are common sources of large doses of iodine.Excessive iodine inhibits the thyroid - too much of a good thing. Deficiency is no good either, results in poorly acting thyroid and goitre. Urine tests for iodine can tell if you're short of it. This is a very useful test in thyroid medicine.
Other tests in thyroid medicineAuto-antibodies - anti thyroid peroxidase, antimicrosomal and antithyroglobulin antibodies - show immune damage, and can current status as they wax and wane.From thyroid medicine back to fibromyalgia page
Also worth a read.
sensible-alternative.com.au
has a good thyroid article.
1About hormone blood levels in thyroid medicine.Hormones are chemical messengers, on their way to someplace in our body, to do a job.We are really only interested in how well the job is done. This may depend on the concentration of the hormone there, and/or its rate of supply (as it may be used up in passing on its message.) In the case of TSH, the receptor is largely expressed on the cell surface, but on addition of TSH, some of the receptors are rapidly internalized2 (with the TSH attached.) That is, the TSH is used up in the process of passing on its message. Measuring the blood concentration is an indirect measure of rate of supply, as demonstrated by the analogy of filling a leaky drum.
Increasing the rate of supply, increases the fluid level in the drum until the rate of leakage again equals that of supply. The level in the drum is like the blood concentration.
Conventional thyroid replacement using thyroxineExcept in otherwise healthy people who recently had surgical or radioactive iodine ablation, it is best to "start low and go slow."This is especially so if someone has heart disease, as speeding up their heart may aggravate angina. Most adults will end up on 100-200 micrograms, but if there is any concern it is best to start with 25mcg. for the first month, and increase by this amount this often. If say, the best dose ends up being 800mcg. per week, this can be done by having 100mcg. 5 days and 150mcg. 2 days. It's long acting, so there's no need to cut tablets to have the same every day.
References for thyroid medicine2. Singh SP, McDonald D, Hope TJ, Prabhakar BSEndocrinology. 2004 Feb;145(2):1003-10.
|
