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The Importance of Thyroid Function written by Trudy Cadoo
Do you struggle with your weight although you are eating a perfectly healthy diet and exercising regularly? Are you feeling anxious, fatigued or experiencing muscle weakness? Have you considered checking out your thyroid function? While none of these symptoms are absolutely specific to thyroid disease alone, they are often signals that something could be wrong with your thyroid.
The thyroid is a butterfly-shaped gland situated in the front part of the neck. It is part of the endocrine system which secretes regulatory hormones into the blood. Production of thyroid hormones depends upon adequate amounts of iodine and the ability of the thyroid to utilize it. The hormones regulate the basal metabolic rate and have an effect on development and growth. Dysfunction of the thyroid is more common in women than men and can cause a number of different symptoms depending on whether the thyroid gland is over functioning or under functioning. Often a mild thyroid imbalance will go unnoticed, with symptoms such as mild weight gain, fatigue, depression and constipation.
Hyperthyroidism is a state of over-activity of the thyroid gland with excessive production of thyroid hormones causing an increased metabolic rate. Hyperthyroidism is far less common than hypothyroidism. Symptoms of hyperthyroidism can include:
Feeling hot and intolerant of hot weather; excessive sweating
Weight loss usually with an increased appetite
Nervousness; anxiety; restlessness; insomnia
High blood pressure; increased heart rate; heart palpitations
Hand tremors and fine tremors of the fingers
Fatigue; muscle weakness
Menstrual periods become very light or stop altogether
Possible swelling of the thyroid gland, referred to as ‘goitre’
Hypothyroidism is a state of under-activity of the thyroid gland with an underproduction of thyroid hormones. The most common cause of hypothyroidism is an autoimmune disease called Hashimoto’s thyroiditis. The body’s own immune system attacks and destroys the thyroid cells, producing inflammation and leaving the thyroid unable to manufacture sufficient amounts of thyroid hormones. This causes the body’s metabolism to slow down, producing symptoms such as:
Tiredness; fatigue; muscle weakness and cramps
Weight gain for no apparent reason
Intolerance to cold weather
Brittle, dry hair; thinning of the hair, including the eyebrows
Slow heart rate; weak pulse
Puffiness of the hands and face
A croaky, hoarse voice
Decreased appetite; constipation
Poor concentration; poor memory; mental confusion
Loss of libido; infertility
FACTORS THAT AFFECT THE THYROID FUNCTION
1. Iodine Deficiency
Thyroid cells are the only cells in the body that can absorb iodine and convert it with tyrosine (an amino acid) into two hormones, thyroxine (T4) and triiodothyronine (T3). Iodine deficiency is the main cause of hypothyroidism worldwide and the leading cause of intellectual disability in babies and children in developing countries. In some developing countries, the population including pregnant mothers, does not have access to seafood and crops are grown in soil deficient of iodine. In Australia, people who rely on tank water are at risk as rainwater lacks iodine, but iodised table salt is readily available and can overcome this problem. However in western countries, the concern with hypertension has resulted in the decreased use of salt and iodine deficiency is again becoming apparent.
Thyroid disorders are closely associated with stress disorders. Adrenaline plays a role in exacerbating the symptoms of thyroid
dysfunction. In hyperthyroidism, the adrenaline receptors are unregulated, increasing metabolic activity, causing anxiety, insomnia and other hyperactive symptoms. In hypothyroidism, nervous system manifestations such as fatigue and depression are intensified by a reduction in the sensitivity of adrenergic receptors.
3. Autoimmune Disorder
Autoimmune disorders occur when the immune system produces antibodies that attack its own tissues. Sometimes this occurs in the thyroid gland. Scientists are not sure why the body produces antibodies against itself. Some think a virus or bacterium might trigger the response, while others believe a genetic flaw may be involved. Three autoimmune disorders of the thyroid are:
Hashimoto’s thyroiditis which is the most common form of under-active thyroid in developed countries such as Australia and America.
Graves’ disease which is the most common form of an over-active thyroid accounting for 85% of all hyperthyroidism.
Postpartum thyroiditis which is an inflammation of the thyroid gland that occurs in 5 to 9% of women during the first six months after giving birth. The exact cause is unknown but women who develop postpartum thyroiditis are likely to have an underlying autoimmune condition that shows in pregnancy. The thyroid usually returns to normal within 12 to 18 months after commencement of the symptoms.
4. Foods that may interfere with thyroid function
Foods such as soy can interfere with the functioning of the thyroid gland to produce thyroid hormones. Other foods that may block the uptake of iodine in their raw state are cabbage, cauliflower, broccoli, kale and kohlrabi, so these must be well cooked.
In susceptible people, gluten can affect the thyroid as it is capable of stimulating the immune system to produce autoantibodies. Research has shown that a high percentage of people with autoimmune thyroid disease are gluten intolerant. Patients who have been diagnosed with a thyroid condition, could consider being tested for coeliac disease.
NUTRIENTS THAT ASSIST THE THYROID FUNCTION
A variety of nutrients, vitamins and minerals are required for healthy thyroid function. The list below is not exhaustive:
1. Iodine – a mineral essential for production of thyroid hormones. Iodine can be found in seafood, seaweed, dairy products and pre-packaged breads. Eating seafood three times a week or using iodised salt in cooking will assist in maintaining good levels of iodine. It is important to note that people with Graves’
disease and other overactive thyroid conditions should consult their General Practitioner before commencing any addition of iodine to their diet.
2. Selenium – this trace element has many important roles in the body, including crucial roles as a cofactor in enzymes essential for production of thyroid hormone. The best dietary sources of selenium include brazil nuts, crab, salmon, poultry, pork and walnuts.
3. Zinc – low zinc levels are associated with poor thyroid hormone production and reduced basal metabolic rate. Foods rich in zinc include oysters, pumpkin seeds, ginger root, eggs, pecans and whole grains.
4. Copper – is needed in small amounts for healthy thyroid function. Copper and zinc compete for absorption so it is possible to become copper deficient if you have been using a high dose of zinc for an extended period of time. Nuts and legumes are a good source of copper and interestingly foods rich in copper are typically even higher in zinc.
5. Tyrosine – an amino acid, is needed for the formation of thyroid hormones. Tyrosine is widely found in foods such as meat, fish, dairy products, eggs, nuts and seeds.
6. Vitamin A – thyroid hormones are required for the conversion of beta-carotene into vitamin A in the body. Therefore if you have hypothyroidism you may be deficient in vitamin A. Food sources of vitamin A are eggs, fish, butter (organic) and full cream milk. Cod liver oil supplements are high in vitamin A. Beta-carotene is found in carrots, sweet potato and pumpkin.
7. Vitamin D – specifically beneficial for autoimmune related thyroid imbalance. Vitamin D is naturally produced by the body when skin is exposed to sunlight. Depending on the season and country where you live, about 20 minutes of sunlight on the legs and arms every day should produce an adequate amount of vitamin D. Vitamin D is found also in fish (such as salmon and sardines), eggs and cod liver oil. Many dairy products are enhanced with vitamin A and D.
THYROID TESTING: SELF TESTING AND CLINICAL TESTS
Thyroid tests you can do yourself
1. Basal Body Temperature – the basal (resting) body temperature is a good indicator of thyroid function. Follow the instructions as indicated:
It is preferable to use a mercury thermometer.
On waking, take your temperature from your armpit before any movement; do not have anything to eat or drink prior to the measurement.
Hold the thermometer in place for ten minutes and continue lying still. Write down your temperature for four consecutive days.
If you are menstruating, only do this test on the second or third day of the menstrual flow.
With a normal functioning thyroid, basal temperature should have a reading of 36.4 – 37.1°C. A consistent reading of 37.1°C or higher may indicate elevated thyroid function. This method is not 100% accurate and should not be relied on solely. It can be helpful when used in conjunction with other thyroid tests.
2. The Thyroid Neck Check – This test is advocated by the American Association of Clinical Endocrinologists. It is a test that allows you to check if there are any changes in appearance of your thyroid.
Holding a mirror out in front of you, look at your neck just under your Adam’s apple and above your collarbone.
Tip your head back, take a sip of water and swallow. If you see or feel any lumps or bulges in this area as you are swallowing, you should see a doctor to get it checked out.
Thyroid nodules are likely to move when you swallow.
Clinical Thyroid Tests
1. Urinary iodine test measures the amount of iodine in a 24-hour urine sample. It is often considered as the ‘reference standard’ for giving a precise estimate of an individual’s iodine excretion and thereby iodine intake.
2. The thyroid function test will give the levels of the following hormones in your blood:
TSH – Thyroid Stimulating Hormone produced by the pituitary gland
Free T4 or FT4 – Free Thyroxine
Free T3 or FT3 – Free Triiodothyronine
In early 2003, the new guidelines for thyroid function tests were issued by the American National Academy of Clinical Biochemistry. Unfortunately some laboratories are still using an outdated reference range. The following statement was extracted from the ANACB press release, issued January 2001. ‘Even though a TSH level between 3.0 and 5.0 mlU/L is in the normal range, it should be considered suspect since it may signal a case of evolving thyroid under activity.’
3. Other Thyroid Tests
Reverse T3 – is an inactive form of the thyroid hormone, T3. It is produced during periods of high stress. High rT3 can leave you with symptoms of hypothyroidism despite a normal thyroid function blood test.
Thyroid antibody tests can test for autoimmune thyroid diseases like Hashimoto’s thyroiditis, Graves’ disease and postpartum thyroiditis. Autoimmune disease of the thyroid can cause both hypo and hyperthyroidism, as the antibodies can either block or stimulate the thyroid receptors.
Often in early stages of thyroid disease, the individual will present to the doctor with various symptoms, ranging from fatigue to an enlarged thyroid gland. Even if the blood test results are normal, the symptoms must be constantly monitored. Thyroid function can be greatly influenced by diet and nutritional intervention. If left undiagnosed, thyroid damage may occur. If you suspect that you have a thyroid problem after reading this article or you have a family history of thyroid disease, I encourage you to see your health care professional to determine what is best for you. This article is for information only and should not be used to diagnose, treat, cure or prevent disease.
Author of this article:
Trudy Cadoo is a Senior Naturopath at Brisbane Livewell Clinic, Chermside. She believes that health is more than the absence of disease. It is the balance of many factors including mental, emotional and physical wellbeing. Trudy uses a wide range of diagnostic tools to identify and treat presenting problems.