Hypothyroidism - A Common Hormonal Problem in CFS
It is now quite clear there is a distinct hormonal disturbance in CFSs with a general suppression of the hypothalamic - pituitary - adrenal axis. It is the pituitary which is the "conductor of the endocrine orchestra". If the pituitary is malfunctioning then this has knock on effects for the thyroid gland, adrenal gland, sex hormones, possibly the pineal (produces melatonin for normal sleep), as well as hormones for growth and urine production.
In practice I invariably measure thyroid hormones (TSH, T4 and T3), often prescribe melatonin, often check adrenal function and very occasionally use sex hormones (mainly testosterone in men). Many CFSs are substantially improved by correcting thyroid hormones and I insist all my CFS patients get fully tested.
Underactive thyroid gland
The problem in CFS is caused by low levels of thyroid hormones in the blood. This can be underactive for three reasons - either the gland itself has failed (primary thyroid failure), or the pituitary gland which drives the thyroid gland into action is under-functioning, or there is failure to convert inactive T4 to active T3. The symptoms of these three problems are the same.
- In primary thyroid failure, the blood tests show high levels of thyroid stimulating hormone and low levels of T4 and T3.
- In pituitary failure, the blood tests show low levels of TSH, T4 and T3.
- In conversion problem, TSH and T4 may be normal, but T3 is low.
There is another problem too which is that the so-called "normal range" of T4 is probably set too low. I know this because many patients with low normal T4 often improve substantially when they are started on thyroid supplements to bring levels up to the top end of the normal range. Indeed Dr Skinner, who is a consultant virologist at Birmingham, has shown how many patients with CFS have low normal levels of thyroxine (T4) and do well when their levels are increased to average levels. The laboratory I use has a normal range of 12-22 pmol/l and I am finding many levels coming back at 12-15. In these patients there is an indication for trying T4, especially if symptoms suggest this. I emphasise that this is a trial - it does not commit one to thyroid hormones for life.
Symptoms and signs of an underactive thyroid
- Anybody with CFS could fit a diagnosis of hypothyroidism!
- Symptoms: lethargy, sensitivity to cold, heat intolerance, mood swings and depression, poor memory and concentration, joint pains and morning stiffness, headaches, vertigo and deafness, pre-menstrual tension, voice changes, loss of libido and susceptibility to viral infections.
- Signs: weight gain, fluid retention, puffy face, puffy eyes, hair loss (classically the outer third of the eyebrows), cold extremeties and dry skin, rashes, eczema and boils, enlargement of the tongue, hoarse voice, hypoglycaemia, constipation, menstrual problems, skin problems and tendency to infections, slow pulse or bradycardia, goitre, infertility, digestive problems, slowed Achilles tendon reflex, carpal tunnel syndrome. Further useful information is the basal body temperature. Use a mercury thermometer to take the temperature in the armpit over 10 minutes immediately on wakening. Temperatures consistently below 97.8 degrees F (36.6 degrees C) indicates slow metabolic rate. Remember that low body temperature can also be caused by poor mitochondrial function - see CFS - The Central Cause: Mitochondrial Failure
Treatment of an underactive thyroid
In deciding whether to treat, one must consider both the symptoms and the blood tests. Many doctors just treat the blood levels. The issue here is that one's personal normal range of thyroid hormones is not the same as the population normal range. Some people feel much better running high normal rather than low normal levels of T4 and T3.
- If the T4 is low and T3 commensurate with a low T4: I would start with thyroxine 50mcgms (25mcgms for a small person or child or someone very debilitated) and increase in 25mcgms increments every month up to 100mcgms (or 75 mcgms in a small person or child or debilitated person) at which point the blood needs retesting. The aim is to get into the middle or upper half of the "normal" range. If I had a patient who was very small or very debilitated I might even start with 12.5mcgms.
- If the T3 is low, and T4 normal: then I would use generic thyroid which is a physiological mix of T4 and T3. I would start with 1/2grain daily for one month, then 1/2grain twice daily for one month, then 1 grain and 1/2 grain daily for the third month at which point the blood need retesting. Take the second dose not later than 4pm or it may interfere with sleep. Some people like to take the second dose at lunch time to get an afternoon boost.
- If the dose of thyroid was too high, then side effects would develop: hotness and sweating, anxiety and feeling "wired", fine tremor and palpitations. In this event, stop the thyroid supplement immediately. Taking additional thyroid will clearly make this situation worse. If in doubt, reduce the dose. Some of my patients do seem to get the symptoms of over-activity despite the blood levels being normal. This is probably due to receptor hypersensitivity and this settles within a few weeks. In this event reduce the dose and then build up slowly.
Some of my patients do seem to get these symptoms of over-activity despite the blood levels being normal. I suspect it is because the body has been long used to inadequate thyroid hormones and the receptors have become more sensitive. In this event I try a lower dose and build up slowly. However some people seem never able to tolerate T4 even in these tiny doses.
Absorption of thyroxine varies with food. It does not matter very much if you take the thyroxine with or without food, so long as you do the same thing every day.
Note that thyroxine is only available on prescription. Before a prescription can be issued, you need to be seen by a doctor who can state that clinically there are no symptoms or signs of thyrotoxicosis. Symptoms would include weight loss, racing pulse, high blood pressure, feeling too hot, becoming hyperactive, anxious or panicky, inability to sleep, tremor or excessive sweating.
Some people who are allergic do not tolerate lactose which is the excipientic thyroxins. In this case I would use thyroid which is excipient free.
I can only supply thyroid hormones with a recent thyroid function test and this clinical assessment. For more details click on link to thyroid function test below.
Thyroxine is inexpensive, but there is a dispensing fee on each order of £5 and I supply enough to be going on with until a further blood test is required. Once stabilised I like to check levels once a year. Obviously your GP needs to be informed.
After three months the levels of T4 and T3 should be rechecked (the tablets should be taken on the day of checking). Blood for testing T3 levels needs to be taken 1-4 hours after taking the T3 tablets. Once the levels are stabilised, then checking only needs to be done once a year. Thyroid hormone levels take one month to stabilise in the blood, so any tests should only be done one month after a dose adjustment.
If you are taking thyroid supplements at any time, it is always possible that you could become thyrotoxic - not through any fault of the tablet but because the thyroid gland suddenly decides to. If you suspect this because you develop symptoms of toxicosis such as hotness and sweating, anxiety, fine tremor, palpitations and possibly sleeplessness, then stop the thyroid supplement immediately and get your levels rechecked.
Treatment with thyroid hormones is nearly always for life.
Re-testing of thyroid function on only T3.
One cannot predict the response to pure T3 simply on the basis of blood tests. The effectiveness of T3 is largely judged clinically. However we do need to use blood tests to monitor therapy to make sure we are staying within or close to population reference ranges for T3. Once a clinical response has been achieved, then is the time to check bloods. One may respond immediately to T3 but one would not give up trying until you had had a trial of T3 for a few weeks. T3 is short acting and needs to be taken in at least 3 separate doses through the day, some people like 5. A rule of thumb is to take 1/2 the daily dose as close to 5am as reasonably possible, 1/4 tablet at midday and 1/4 tablet in late afternoon – this is to copy the normal circadian rhythm. In Nature levels of T3 peak at 5am. So any blood test should be done at least 6 hours after the first daily dose and 4 hours after another. The best option may be to arrange a blood test in the morning and omit the early morning dose.
Taking pure T3 does result in odd blood tests! The T4 will be markedly suppressed. The TSH is likely to be suppressed because the problem in T3 hypothyroidism is often receptor hormone resistance. The T3 should be within or close to population references ranges. The eventual dose depends on clinical and biochemical assessment.
The Pulse Test
For some people, their pulse rate at rest parallels the activity of their thyroid gland. This can be particularly helpful to a brittle minority whose levels of thyroid hormone fluctuate widely with just minor adjustments to the daily oral dose. A normal pulse lies between 65 and 75 beats per minutes at rest.
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