Endocrinology, or the study of hormones, is an immensely complex field in which each gland – each hormone produced in each gland – can serve multiple purposes, some of which are understood and others which are still in the early stages of discovery. Or even entirely unknown! The best way to study hormones is perhaps individually, or at the least in concert with the gland which produces it, but sometimes this is not ideal.
Take the thyroid, for instance. It releases thyroxine and triiodothyronine which aid the metabolism and make use of dietary iodine. But the thyroid does not operate alone: it relies on the pituitary gland and the hypothalamus – both found in the brain – to let it know when it should manufacture and release the two hormones. Thus far, doctors have found it most efficient to work to restore and maintain hormone levels within ‘normal’ parameters. This means that if a level of one hormone is between 5 and 10 percent within 97 percent of the population, this becomes accepted as the ‘norm’ and medical professionals work to these criteria. For the most part, this is a sensible and cost-effective plan, with only a very few people – the outliers – needing more time and attention to find their optimum levels of the hormone in question.
In hypothyroidism, when the thyroid is underactive and does not produce enough of the two hormones, doctors will supply synthetic hormones which work to fulfil the functions that the faulty thyroid is not coping with. Rather than say ‘thyroxine’ and ‘triiodothyronine’ each time, the two hormones – and their replacements – are called T4 and T3 respectively. The names indicate the number of iodine molecules the hormone is carrying: T3 carries three and T4 carries four. T4 replacements are more common, and for most thyroid patients this is fine as the body converts the T4 into T3 quite readily. T3 is what might be called the active version of the hormone and is responsible for many of the benefits and reactions experienced in the body. By using mainly T4 replacements, doctors are simply following the body’s directive. We naturally produce more T4 than T3 which is then converted as needed.
Around 15 percent of thyroid patients find that T4 replacements do not work for them, or that they do not work effectively. It is as yet unknown why this small percentage of patients cannot tolerate or convert synthetic T4, but it is accepted that for them, a regimen of T3 works best.
Whenever taking a thyroid treatment, there are a few points to consider for hailing the treatment as a success or writing it off as a failure. Firstly, allow enough time for the medication to begin to work. Its effects are cumulative, and you may only get a sense of your new health after four to six weeks. Make sure you allow the doctors to tailor your dose. Thyroid hormones are incredibly potent (T3 being even more so) and even a slight variation in the dosage can make a huge difference to the way you feel. The only way to get it right is by trial and error over a period of time, to get your numbers into the right parameters. And finally, do not be tempted by supplements that promise to boost thyroid health: these can often contain further amounts of thyroid hormones which will interact – often badly – with your prescribed medication!