Thyroid Disease
What is it?
The thyroid gland, situated in the front of the neck, is responsible for producing hormones which control our metabolism.
Symptoms of an under-active thyroid gland
• Weight gain
• Low body temperature
• Constipation
• Hair loss
• Dry flaky skin
• Fluid retention
• Slow reflexes
• Fatigue
• Rapid ageing
• Slowness of thought and cognition
If there is an overproduction of thyroid hormone (hyperthyroidism) the whole metabolism speeds up giving rise to symptoms such as a rapid heart beat, increased appetite, weight loss, diarrhea, intolerance of heat, irritability, tremor, malaise and muscle weakness. This is called hyperthyroidism or thyrotoxicosis. The commonest cause of thyrotoxicosis is Graves' disease which is an autoimmune condition (see Autoimmune Disease) often associated with protruding eyeballs (exopthalmus).
An underactive thyroid (hypothyroidism) results in a slowing of the metabolism with symptoms such as fatigue, weight gain, intolerance to cold, poor memory, depression, puffy eyes, constipation and dry, coarse skin and hair. Hypothyroidism is commonly the end result of autoimmune disease, usually Hashimoto's disease or due to shrinkage or degeneration in the thyroid gland due to ageing or poor nutrition.
A goitre is an enlargement of the thyroid gland. A goitre may be associated with increased, decreased or normal levels of thyroid hormone, depending on the cause. Some causes of goitre include Graves' disease, Hashimoto's disease, viral infection, iodine deficiency, pregnancy, puberty and tumors within the thyroid gland. Nodular changes producing multiple cysts in the thyroid gland is a common cause of goiter. Goitres may sometimes reach very large sizes and compress the trachea (wind pipe) or esophagus causing difficulty breathing or swallowing.
Thyroid Dysfunction & Menopause
Thyroid problems are very common especially in women around the time of the menopause. The most common type of thyroid problem is underactivity of the gland, which is called hypothyroidism. In this disorder the thyroid gland is not able to manufacture sufficient amounts of thyroid hormone. Thyroid hormone controls the metabolic rate of the body speeding up the rate at which the cells convert food energy into physical energy.
Thyroid Hormones
The thyroid gland produces the hormone called Thyroxine, which is also known as T4. Most of the Thyroxine (T4) is converted in the body into a more active form of thyroid hormone, which is known as Triiodothyronine or T3.
T3 has 10 times the ability to stimulate the thyroid receptors on the cells. Both T4 & T3 stimulate the energy factories inside the cells to burn food calories at a faster rate. This is why those with an over-active thyroid gland lose weight, even though they are eating much more than normal.
Tests of the Thyroid Gland
The function of the thyroid gland can be accurately checked by measuring the levels of thyroid hormone in the blood. A goitre may be investigated by means of a nuclear or ultrasound scan. Your doctor can arrange this. A lump in the thyroid gland may require a fine needle biopsy of the gland.
Thyroid function tests are used to
Diagnose an underactive thyroid (hypothyroidism) and an overactive thyroid (hyperthyroidism). Evaluate thyroid gland activity. Monitor the response to thyroid therapy.These tests include the thyroid-stimulating hormone test (TSH), the thyroxine test (T4), the triiodothyronine test (T3)The blood tests for thyroid gland function should ideally measure the following three hormones –
Hormone Normal Range
Thyroid Stimulating Hormone (TSH) 0.5 to 5.0 mU/L
Free T 4 9.0 to 24.0 pmol/L or 4-11 ug/dl
Free T 3 2.2 to 5.4 pmol/L or 110-230
Not all laboratories measure or record thyroid hormone levels the same way. Each laboratory will provide a range of values that are considered normal for each test.
Results
If the T 4 and/or T 3 levels are found to be below the normal ranges, and the TSH (Thyroid Stimulating Hormone) is found to be above the normal range, we can say that the thyroid gland is under active. Most doctors consider the sensitive thyroid-stimulating hormone (TSH) test to be the most accurate measure of thyroid activity. By measuring the level of TSH, doctors can determine even small problems in thyroid activity. Because this test is VERY sensitive, abnormalities in thyroid function may be determined before a patient complains of any symptoms. TSH "tells" the thyroid gland to secrete the hormones thyroxine (T4) and triiodothyronine (T3). Before TSH tests were used, standard blood tests measured levels of T4 and T3 to determine if the thyroid gland was working properly. The triiodothyronine (T3) test measures the amount of this hormone in the blood. T3 is normally present in very small amounts, but has a significant impact on metabolism. It is the more active component of the thyroid hormones.
Abnormal thyroid function results may be due to:
• Acute thyroiditis (inflammation of the thyroid gland)
• Thyrotoxicosis (acute severe elevation of thyroid hormones)
• A tumor (benign or malignant) within the thyroid gland that produces large amounts of thyroid hormone (toxic thyroid adenoma)
• Thyroid failure in infants (cretinism)
• Underactivity of the thyroid gland (Hypothyroidism)
• Overactivity of the thyroid gland (Hyperthyroidism)
• Kidney failure
• Endemic deficiency of minerals such as iodine and selenium
• Auto-immune disease - known as Hashimoto's thyroiditis. This is an autoimmune condition as the bodies own immune system is attacking the thyroid gland. All autoimmune conditions have a basis in poor liver function as a poorly functioning liver causes hyperstimulation of the immune system which then turns on itself.
• Viral infection of the thyroid gland
• Genetic factors - there is often a family history of thyroid diseases
• Contrast X rays using iodine
• Medications such as Heparin, Heroin, Lithium, Phenytoin, Estrogen therapy, Propranolol, Oral contraceptives, Anabolic steroid drugs or male hormones.
• Pregnancy