The Thyroid Gland
The thyroid gland is shaped like a large butterfly whose wings enfold the middle part of the windpipe in the neck. It produces a hormone called “thyroxin” which goes directly into the bloodstream, reaching every cell in the body where it controls the rate at which cells ‘burn up’ energy.
Have you ever had problems with your car when the engine was running too slow and kept stalling? Remember how the garage mechanic simply turned up that little screw on the carburettor and the engine speeded up and the problem disappeared?
Well it is the same with cells. You may picture each cell having its own little carburettor screw which is turned upwards by “thyroxin”; the more thyroxin in your body, the faster the engine revs and vice-versa.
It is now apparent what effects there will be from too much or too little “thyroxin” in the bloodstream:
- Energy Level. Too little thyroxin will produce tiredness and fatigue, low energy levels, often sleeping all the time; too moo much thyroxin finds the patient over-active with too much nervous energy often with insomnia.
- Weight. Too little thyroxin means the patient cannot burn off energy and therefore weight tends to go up; too much thyroxin tends to produce weight loss.
- Temperature Toleration. Body heat is generated by cells burning up energy; therefore insufficient thyroxin finds the patient feeling cold and excess thyroxin makes her feel too warm.
- The skin. Cells in the skin need to take up energy to produce their natural oils; low thyroxin levels therefore make the skin go dry and flaky whereas excess will make it sweaty and greasy.
- The Bowels. The muscles of the bowel contract to propel the food onwards; shortage of thyroxin will therefore cause constipation and excessive amounts will produce diarrhoea.
- The heart. The heart beats too slowly if short of thyroxin and too quickly when thyroxin is in excess.
- Appetite. Tends to be poor with low levels of thyroxin and excessive when levels are high.
- Periods. They tend to be too heavy and frequent when there is too little thyroid and light and infrequent when there is too much.
If your thyroid gland is under-active, then replacement thyroid is given by mouth in the form of thyroxin tablets; the ideal dose varies from patient to patient, though once this is found it rarely needs to be changed. Because thyroxin is lost only very slowly from the body, it accumulates and so you will only know if the chosen dosage is right for you after a period of about three weeks.* Then you can check your thyroid status yourself on the chart overleaf and a blood test can also guide us that we are at the right level.
If your thyroid gland is over-active, then this can be corrected either by medications (which need to be taken for at least 18 months), a dose of radioiodine or surgical removal of most of the thyroid. Again checking that your body is ‘thyroid-normal’ is essential for follow up.
Good Luck!
Bernard Shevlin
*The elimination half-life of thyroxine is 6-7 days in euthyroids, 9-10 days in hypothyroids and 3-4 days in hyperthyroid. At least 5 x plasma half lives are needed to reach steady state.
Thyroid Self-Evaluation
Is your body receiving too much or too little thyroid hormone? You can self-test by putting a cross on the appropriate section of the scale below for each system; the end-arrows represent the extremes of possibility and if you are perfectly normal, your crosses should all be roughly in the middle. If you have too much thyroid, your crosses will lie to the right; if not enough, they will lie to the left. Good Luck! Bernard Shevlin
Rapidly gaining weight for no reason Rapidly losing weight for no reason
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Extremely tired all the time Far too much nervous energy
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Can’t Stand the cold Can’t Stand the heat
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Severe Constipation Severe Diarrhea
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Poor Appetite Enormous appetite
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Heart beats too slowly Heart beats too quickly
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Dry flaking skin sweaty, greasy skin
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Difficulty staying awake Difficulty getting off to sleep
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