THE THYROID GLAND

alt The thyroid is a gland located in the front, at the bottom of the neck, with 2 lobes, joined across the middle, one each side of the windpipe. It is the body’s thermostat, regulating the speed at which the body’s cells burn their fuel.

The thyroid produces several hormones, the most important being Thyroxin or T4. This is converted in the tissues of the body to Tri iodothyronine or T3, which stimulates the cells to burn fuel faster.

The thyroid is controlled by the pituitary gland in the brain. When it detects that the levels of thyroid hormones are dropping too low, the pituitary produces Thyroid Stimulating Hormone [TSH], which tells the thyroid to produce more thyroid hormone,T4. Conversely it reduces production when it detects that the levels are too high.

Why does it go wrong?

Thyroid problems are more common in women, and are also more common after age 50, with the exception of post partum thyroiditis and Graves’  disease, which is usually seen under 40 years of age.

Things may go wrong anywhere between the pituitary gland, the thyroid itself, in the blood stream, or the cells of the body. Goitre simply means a swollen thyroid gland, and this may be due to any of several causes:

The thyroid may become overactive due to:

  • Growth of either one or several nodules in the thyroid, which begin to produce hormones independently of the pituitary’s control.
  • Graves' disease, in which the immune system makes antibodies that act like TSH, causing the thyroid to make more thyroid hormone than your body needs. This condition is associated with bulging eyes.
  • Hashimoto’s disease, in which the immune system also makes antibodies but which damage thyroid cells and interfere with their ability to make thyroid hormone.
  • The gland can become inflamed, when there is a transient overactivity followed by under activity. This can also occur after giving birth, known as post partum thyroiditis, but may occur at any time.

Excessive ingestion of iodine may paradoxically reveal a potential thyroid problem, especially in nodular disease.

It may be underactive  due to:

  • Iodine deficiency; the thyroid needs iodine to manufacture T4, and if it is lacking in the diet, the thyroid will become enlarged.
  • Pituitary failure, in which the pituitary gland fails to send TSH to the thyroid, which then fails to produce thyroid hormone.
  • Failure of the gland itself, often following treatment for hyperthyroidism, or due to the patient’s own antibodies attacking the gland, as in Hashimoto’s Thyroiditis.
  • Certain medications such as Lithium and Amioderone may interfere with the manufacture of T4.
  • It can be congenital, in other words the baby is born with an underactive thyroid. If untreated this leads to severe developmental impairment known as cretinism. Fortunately it is rarely seen these days due to increased awareness by medical personnel.
  • Certain foods may also interfere with the thyroid’s metabolism. These include soy, which contains goitrogens, [in other words substances that induce a goitre], natural substances that are also present in broccoli, kale, millet, peanuts, cabbage, pine nuts, turnips and Brussels sprouts but are destroyed by cooking. Goitrogens can block the uptake of essential iodine from the blood. However, in clinical trials where soya is added to people's diet, no harmful effects on thyroid function were seen.
  • The thyroid may develop nodules that are inactive, and these should be monitored as there is a small chance of cancer. If you find a lump in your neck, it should always be shown to a doctor, who can decide whether further tests are needed.

What happens when it goes wrong?

When it is overactive [hyperthyroidism] there is sometimes swelling of the gland in front of the neck [Goitre]. The patient is usually jumpy and nervous, will dislike heat, and may have diarrhoea, weight loss, and menstrual upset. In Grave’s disease the patient may also have large staring eyes. In elderly patients the only sign may be heart failure, due to the extra work being done by the heart.

When it is underactive [hypothyroidism] the opposite occurs. The patient is slow, gains weight, with a puffy face known as myxoedema, dry hair and skin, is constipated, cold, and may have irregular periods. The eventual end result of this if untreated can be coma and death.

What tests are available?

Commonly a TSH, T4 and sometimes T3 are measured. These tests tell us how the pituitary and thyroid are working in comparison to the rest of the population, as normal levels are calculated by taking the average for several thousand  people.

If the thyroid is underactive, the TSH will be high, as the brain is trying to stimulate the gland to work harder, and vice versa.

If the patient is suspected of having an autoimmune problem, then thyroid antibodies can be measured.

These tests do not however tell us whether the body is responding to the hormones.

An alternative method of assessing whether a thyroid is underactive was devised by an American doctor, Broda Barnes, who sensibly realised that if the thyroid is underactive, the body’s temperature drops. Thus, as long as there is no infection causing fever, measurement of body temperature should give a guide as to thyroid function.

The Barnes’ method is as follows:

  A mercury thermometer should be shaken down as low as possible [well below 37 deg C]

  On waking in the morning, before getting out of bed, and before taking anything by mouth, place the thermometer in the armpit for 10 minutes, lying still.

 The normal temperature by this method is 36.6 – 36.8 deg C

 Lower than 36.4deg C is suggestive of thyroid under activity.

Please note that in women who are having normal periods, this should be done on the second to fourth day of the period. If she is of reproductive age [premenopausal], but not having periods, then take a reading once a week for 4 weeks.

What is the treatment?

An overactive thyroid may have several causes as mentioned above. Usually a TSH and T4 will be done to establish the diagnosis. This may be followed by ultrasound examination to determine whether there are nodules, or whether the whole gland is enlarged as in Graves’ disease. A radioactive uptake scan may also be needed to ascertain whether the nodule[s] are responsible for the overactivity.

If the thyroid is underactive as shown by the TSH and T4, it is quite simply treated by replacing the lacking hormone with a synthetic version, thyroxine. This will need to be continued lifelong.

What else can I do?

If you suspect that you may have a thyroid problem or you notice some swelling in your neck, please see your Doctor and allow him to do the necessary tests.

If your thyroid is overactive and you are losing weight, try to eat plenty of protein such as meat, cheese and eggs and take a multivitamin and mineral supplement. You may be given a medicine called Carbimazole, which reduces the production of T4. There are some precautions to take with this medicine, so follow your Doctor’s advice.

If your thyroid is underactive, try to include supplements containing chromium and manganese, and eat a high protein, low carbohydrate diet as protection against insulin resistance. Exercise, even daily walking, can help to control the weight gain that results from hypothyroidism.

It has been reported that Calcium and Chromium picolinate supplements may impair the absorption of thyroid medications. The two should therefore be taken three to four hours apart. Coffee and fibre supplements may also have a similar effect, so patients should not take these at the same time as the medicine.

Both iodine deficiency and excess have significant risks, and supplementation should be done under medical supervision. Supplemental iodine may cause symptom flare-ups in people with Hashimoto’s disease because it stimulates autoimmune antibodies, and may uncover a potential nodular thyrotoxicosis. The amount in foods is largely dependent on levels in the soil and in iodised salt, however frequent intake of foods such as seaweed [kelp] or alternatively avoidance of all iodized salt may send warning signals.

Vitamin D: Vitamin D deficiency is linked to Hashimoto’s disease, according to a study showing that more than 90% of patients studied were deficient. However, it’s unclear whether the low levels were the direct cause of Hashimoto’s or the result of the disease process itself. Hyperthyroidism, particularly Graves’ disease, is known to cause bone loss, which is compounded by the vitamin D deficiency commonly found in people with hyperthyroidism. This bone mass can be regained with treatment for hyperthyroidism, and adequate bone-building nutrients, such as vitamin D and Calcium are particularly important during and after treatment. Foods that contain some vitamin D include fatty fish, milk, dairy, eggs, and mushrooms. Sunlight also is a potential source, depending on the season and latitude.

Selenium: The highest concentration of selenium is found in the thyroid gland, and it is used to produce and regulate T3. It can be found in foods such as shrimp, tuna, calf’s liver, button and shitake mushrooms and Brazil nuts.

Zinc, Iron and Copper: Low levels of zinc have been linked to low levels of TSH [i.e. overactivity of the thyroid gland],and iron deficiency has been linked to decreased thyroid activity. Copper is also necessary for the production of thyroid hormones. These trace minerals are found in calf’s liver, spinach, mushrooms, turnip greens and Swiss chard.

Omega-3 Fats are found in fish or fish oil, and play an important role in thyroid function, and many help your body’s cells become more sensitive to thyroid hormone.
Antioxidants and B Vitamins: The antioxidant vitamins A, C and E can help your body neutralize oxidative stress that may damage the thyroid. B vitamins help to manufacture thyroid hormone and play an important role in healthy thyroid function.

What Should You Avoid Eating for Thyroid Health?

Aspartame: There is concern that the artificial sweetener aspartame, sold under the brand name Nutrasweet, may trigger Graves’ disease and other autoimmune disorders in some people by triggering an immune reaction that causes thyroid inflammation and thyroid autoantibody production.

Gluten: Gluten is a potential goitrogen and can also trigger autoimmune responses (including Hashimoto’s Thyroiditis) in people who are sensitive. Gluten is found in wheat, rye and barley, along with many processed foods.


Thanks to CNCA for dietary advice


 
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