The THYROID GLAND AND GOITER: Ating Alamin

Butterfly-shaped organ in front of the neck The thyroid gland is the largest organ specialized for endocrine function in the human body. It is located in the neck in front of the windpipe (trachea), below the Adam’s apple (thyroid cartilage). In adults, it can weigh up to approximately 10-20grams.

What Does Your Thyroid Gland Do for You? Produces Two Hormones Called Thyroxine (T4) Thyronine (T3) Regulates Metabolism so Your Cells Function Properly Affects Every Cell in the Body The major function of the thyroid cells is to secrete a sufficient amount of thyroid hormones, primarily tetraiodothyronine (T4) and to a lesser extent, triiodothyronine (T3). Although T4 is the major hormone produced, it is T3 that is active. The thyroid hormones promote normal growth and development and regulate a number of homeostatic functions, including energy and heat production.

Thyroid Hormone Affects Many Organs and General Health Eyes Lungs Brain Heart The thyroid hormone affects all the cells in the body. We will discuss its more evident effects on our body. Thyroid hormones increase oxygen consumption and heat production in all tissues except the brain, spleen, and testis. It contributes to the increased oxygen consumption of the whole body even at rest (basal metabolic rate). That is why in hyperthyroidism the person always feel hot even when he/she is in cool weather or environment, and the converse happens in hypothyroidism. Thyroid hormones increase the strength of contraction or pumping power (positive inotropic effect) and the number of beats in a minute (positive chronotropic effect) of the human heart. That is why the heart beats so fast in hyperthyroidism, and slow in hypothyroidism. Thyroid hormones stimulate the motility of our gut, which can result in increased motility and diarrhea (increased frequency of bowel movement in a day) in hyperthyroidism and slowed bowel transit and constipation in hypothyroidism. Thyroid hormones stimulate stimulate increased production or structural proteins. In hyperthyroidism there is loss of muscle tissue, increase in the speed of muscle contraction and relaxation, the opposite in hypothyroidism. Thyroid hormones are essential for normal development of the central nervous system, and failure of the fetal thyroid function results is severe mental retardation. In adults, this is seen as hyperactivity of hyperthyroid persons and sluggishness of hypothyroid ones. Liver Kidney Skin GI Tract Uterus

Brain function, memory, concentration Muscle movement Iodine Thyroid Hormone Thyroid hormones are unique in that they contain 59-65% of the trace element iodine (I). Iodine is integral to the thyroid hormones’ composition, hence the name triIODOthyroinine (T3) and tetraIODOthyronine (T4). That is why too much or too little iodine result in deleterious effects. So let’s talk about iodine. Iodine enters the body in food or water in the form of iodide or iodate ion, the iodate ion being converted to iodide in the stomach. In the course of a million years, iodine has been leached from the soil and washed down into the oceans, so that in mountainous and inland areas the supply of iodine may be quite limited, whereas the element is plentiful in coastal areas. The thyroid gland concentrates and traps iodide and produces and stores thyroid hormones. The WHO recommends optimal daily iodide intake of 150micrograms for adults; for infants (up to 1year old) 50 micrograms; for children ages 1-6years 90micrograms; and for children ages 7-12 years, 120micrograms. Pregnant and breastfeeding mothers have the highest requirement, 200 micrograms, because they have to take in for themselves and their unborn infant. If iodide intake is below 50micrograms per day, the thyroid gland is unable to make enough thyroid hormones, and the thyroid enlarges (hypertrophies) and the result is goiter and hypothyroidism. Brain function, memory, concentration Muscle movement Cholesterol melting Normal heart beat

Any enlargement of the thyroid gland GOITERS Any enlargement of the thyroid gland “Bosyo” Any enlargement of the thyroid gland is called goiter or “bosyo” in the vernacular. Everybody has a thyroid, but only those who have enlarged thyroid have goiter.

This is how a goiter looks likes

G O I T E R These are also goiters that have been left unattended for several years. They are not very nice to look at.

GOITERS - Diffuse Structure Function - Euthyroid - Hyperthyroid - Nodular Function - Euthyroid - Hyperthyroid - Hypothyroid Remember! Goiter means an enlarged thyroid gland! To further differentiate one goiter from another, we have to consider two things: structure and function. When you consider the structure of the goiter, it may be diffuse or uniformly enlarged; or it may be nodular, meaning, you can feel or see marble- or ball-like structures in the goiter itself. The first illustration of the lady facing forward has a diffuse goiter. The illustration of the man facing left and the picture of the lady also facing left is an example of nodular goiter. When you consider function, it means that the thyroid gland may be hyperactively functioning, hence, HYPERthyroid; not functioning enough, hence, HYPOthyroid; or functioning just right or normally, hence, EUthyroid There may be different combinations of structure and function in the thyroid. So, one may have a diffuse hyperfunctioning (toxic) goiter, diffuse hypofunctioning goiter, or diffuse but normally functioning (nontoxic) goiter. The same hold true for nodular goiters – nodular hyperfunctioning (toxic) goiter, nodular hypofunctioning goiter, or nodular but normally functioning (euthyroid) goiter. On the other hand, the thyroid may not be enlarged at all, so there is NO goiter, but it may be hyperfunctioning (hyperthyroidism) or hypofunctioning (hypothyroidism).

When the Thyroid Doesn’t Work Hyperthyroidism Hypothyroidism Remember hyperfunctioning thyroid = HYPERthyroidism hypofunctioning thyroid = HYPOthyroidism normally functioning thyroid = EUthyroidism

When the Thyroid Doesn’t Work Hyperthyroidism Too Much Thyroid Hormone Metabolism Speeds Up Hypothyroidism Too Little Thyroid Hormone Metabolism Slows Down Hyperthyroidism = too much thyroid hormone is produced = metabolism speeds up. Everything is up or fast! Hypothyroidism = too little thyroid hormone is produced = metabolism slows down. Everything slows down!

Two Common Types of Thyroid Disease The lady on the left, has diffuse toxic goiter, also known as Grave’s disease The lady on the right is hypothyroid. It is not evident just by looking at the picture whether she has a goiter or not Hyperthyroidism Hypothyroidism

Signs and Symptoms of Hyperthyroidism Bulging Eyes/Unblinking Stare Menstrual Irregularities or Light Period Excessive Vomiting in Pregnancy First-Trimester Miscarriage Family History of Thyroid Disease or Diabetes Nervousness Irritability Difficulty Sleeping Swelling (Goiter) Frequent Bowel Movements Warm, Moist Palms Hoarseness or Deepening of Voice Difficulty Swallowing Rapid or Irregular Heartbeat Infertility Weight Loss Heat Intolerance Increased Sweating Persistent Sore or Dry Throat

Signs and Symptoms of Hypothyroidism Tiredness Forgetfulness/Slower Thinking Moodiness/ Irritability Depression Inability to Concentrate Thinning Hair or Hair Loss Loss of Body Hair Dry, Patchy Skin Weight Gain Cold Intolerance Elevated Cholesterol Muscle Weakness or Cramps Constipation Infertility Menstrual Irregularities/ Heavy Period Slower Heartbeat Difficulty Swallowing Persistent Dry or Sore Throat Hoarseness/ Deepening of Voice Swelling (Goiter) Puffy Eyes

What causes Thyroid Diseases ? The “Hidden” Health Problem

What causes thyroid diseases ? Iodine deficiency disorder Surgical Radioiodine therapy Autoimmune diseases What causes thyroid disease? As explained earlier, iodine plays a very important role in the production of thyroid hormones. If iodide intake is below 50micrograms per day, the thyroid gland is unable to make enough thyroid hormones, and the thyroid enlarges (hypertrophies) and the result is goiter and hypothyroidism. If a patient had a previous operation of the thyroid, as in total thyroidectomy, he will develop hypothyroidism because the site for thyroid hormone production has been completely removed. This is easily prevented by the prescription of thyroid hormone tablets as replacement for the lost endogenous thyroid hormones. The same principle operates in patients who had undergone radioactive iodine therapy. Radioactive iodine (I-131) is given as treatment for diffuse toxic goiter and thyroid cancer. What it does is to “melt” the thyroid gland so that the hyperactivity ceases. In thyroid cancer it is given as an adjunct to surgery (total thyroidectomy) to “melt” thyroid tissue that is not visible to the naked eye. In persons with autoimmune disease, what happens is that the immune system perceives the person’s own body, in this case the thyroid, as foreign and thus attacks it. There is a resultant inflammation (thyroiditis) and destruction of the thyroid gland and inadvertent release of thyroid hormones. A person is predisposed to autoimmune thyroiditis usually after a viral infection

Clinical Expression of Iodine Deficiency Fetus Neonate Miscarriages Stillbirths Neurological cretinism Impaired intellectual function Increased perinatal mortality Increased infant mortality Neonatal goiter Cretinism Impaired intellectual function

Clinical Expression of Iodine Deficiency Child & adolescent Adult Goiter Hypothyroidism Impaired intellectual function Retarded physical development Goiter Hypothyroidism and poor intellectual and physical performance

Sources of Dietary Iodine Iodine in soil, water and crops Seafood Dairy Products Iodised salt and other fortified foods Medicines/health foods/supplements Other adventitious sources

Myths and Facts on Thyroid Diseases

ON FOODS Myth Eating carrots, cabbage, root crops can cause goiter. Fact These foods have goitrogens. But you have to eat a truckload of these foods in a short time before you develop goiter. This is a classic old wives tale! Eating the above-mentioned foods will not cause goiter unless you eat a truckload of them in your lifetime.

ON FOODS Fact Myth Drinking cold drinks is bad if you have goiter. The temperature of the food or drink has no effect on the thyroid gland since it is not located in the alimentary tract. The temperature of the food or drink has no effect on the thyroid gland since it is not located in the alimentary tract

ON FOODS Myth Eating seafoods can cure goiter. Not eating seafoods can cause goiter Fact Seafoods are important for their iodine content but can not cure goiter. A person with iodine deficiency may develop goiter. Seafoods are rich in iodine. Iodine is needed by the thyroid gland to produce thyroid hormones; and if iodine is deficient, thyroid hormone production is not sufficient and the thyroid gland may enlarge (goiter). Eating seafoods as well as iodine-enriched salt or food may help in the prevention of goiter and hypothyroidism. However, once a goiter develops, eating seafoods is not enough to cure it. If a person is unable to eat seafoods but his food is seasoned by iodine-enriched salt, this may still be enough to supply his daily requirement of iodine such that goiter and hypothyroidism may still be prevented.

ON FOODS Myth Herbal medicines are effective in treating goiter and other thyroid problems. Fact Contents of herbal medicines are often not specified; their efficacy to treat is still in question. No herbal medicine has been studied and proven to treat goiter. In addition, their safety has not been established either; and they may have may have adverse effects on a person’s kidneys and liver. It is best to seek consultation with a physician prior to taking any medications for proper direction and guidance.

ON FERTILITY Myth A person with goiter becomes infertile Fact Simple goiter does not affect fertility of both sexes. It is abnormal thyroid function that affects fertility Remember structure and function of the thyroid gland are two entities that have to be considered. The simple enlargement of the thyroid gland (goiter) has no effect on a person’s fertility.

ON FERTILITY Myth Radioactive iodine treatment for hyperthyroidism will lead to infertility. Fact Radioactive iodine only concentrates in the thyroid gland and does not affect other organs

ON PREGNANCY Myth Bearing down during labor can cause goiter Fact Iodine deficient pregnant women develops goiter to compensate for thyroid hormone deficiency. It is noted after delivery when increased weight is resolved

ON PREGNANCY Myth Goiter, if present, indicates caesarean section Fact Bearing down during labor does not affect the size of goiter

ON PREGNANCY Myth Any drug for the treatment of thyroid problem should be discontinued once the patient becomes pregnant Fact If the medication is for hyperthyroidism or replacement therapy, the patient should be referred to an endocrinologist for dose adjustment

ON PREGNANCY Fact There is an increased risk for miscarriage if medications are discontinued Fact Patients with inadequate replacement therapy have abnormal platelet function which may lead to prolonged bleeding during labor

ON PREGNANCY Myth All mothers with thyroid diseases will deliver infants with thyroid problems Fact Mothers with circulating thyroid antibodies are more likely to have infants with thyroid problems Antithyroid medications traverse the placenta and may cause transient hypothyroidism in the baby Pregnant women who have hypothyroidism to begin with may deliver infants who are hypothyroid IF their thyroid hormone replacement dose is inadequate. This is because the thyroid begins to function in the human fetus at about 11weeks in the mother’s womb. Prior to this time, the fetal thyroid does not concentrate iodine. Hence, the fetus is completely dependent on his mother’s thyroid hormone stores. Remember! Thyroid hormones are important for early fetal brain development. If it is deficient especially during the earlier part of the pregnancy, the fetus’ nervous system will not develop optimally and the infant may be born with mental retardation of varying degrees. Thus, it is pertinent for women with hypothyroidism contemplating pregnancy or who find that they are pregnant to immediately inform their physician or endocrinologist for proper adjustment of their thyroid hormone dose. If this is done, the fetus will not develop hypothyroidism.

ON VARIOUS TREATMENT MODALITIES Myth Radioactive Iodine Treatment can cause cancer Fact There has been no report that it can cause cancer There is no chromosomal abnormality in children born to mothers who received the treatment

ON VARIOUS TREATMENT MODALITIES Myth Radioactive Iodine Treatment cannot be given to individuals in their reproductive age Fact 131 Iodine concentrates only in the thyroid gland Fertility is affected by the abnormal thyroid functional status (hyperthyroidism or hypothyroidism) Radioactive iodine may be given to persons in the reproductive age. However, if there is a desire for a woman to get pregnant or for a man to father a child, it is advised as a matter of precaution, to avoid undue exposure of the fetus to radiation.

ON VARIOUS TREATMENT MODALITIES Myth Radioactive Iodine Therapy leads to hypothyroidism Fact Even without intervention, the gland will shrink in > 10 yrs time, due to continuous inflammation and fibrosis eventually leading to hypothyroidism The dose of radioactive iodine given is carefully calculated to achieve euthyroidism when it is being given as treatment for toxic goiter. However, over time, some patients indeed progress to hypothyroidism. This is why periodic follow up with your physician is necessary so that he may readily detect if thyroid hormone levels or stores are going down and whether you would need thyroid hormone replacement.

ON VARIOUS TREATMENT MODALITIES Myth Patients who receive Radioactive Iodine uptake and therapy should be isolated Fact No isolation is necessary for 131 Iodine uptake and therapy for hyperthyroidism Only patients who receive high dose treatment for cancer should be isolated in a leaded room Radioactive iodine (I131) is used for treatment of toxic goiter and thyroid cancer; but it is also used for diagnostic purposes, to ascertain the activity of the thyroid gland. This test is called the I-131 thyroid scan and uptake. In this test a very minute amount of radioactive iodine is used; thus the patient who undergoes this test need not be isolated. As treatment however, especially for thyroid cancer, a high dose is given of up to 100 to 200mCi. The patients who receive this will need to be admitted in the hospital and isolated for about 4 – 5 days until the radiation count is usually <2.5mRads. When this level of radiation is achieved, the patient may be safely allowed to re-circulate in society. However, as an added precaution, no intimate and prolonged contact especially with pregnant women and children is advised.

SURGERY Myth Surgery is the ultimate treatment for all thyroid diseases Fact Surgery is indicated for thyroid cancer, multinodular goiter, and in big goiters causing compression symptoms Not all thyroid disease requires surgery as treatment. There are oral medications, radioactive iodine therapy for specific indications. Your doctor knows best what the best option for your particular condition is. It is best to consult your friendly endocrinologist as to your options.

SURGERY Myth Patients who get operated on for goiter lose their voice Fact This is rare if thyroidectomy is done by an experienced surgeon Laryngeal nerve damage is higher on reoperation Patients who undergo thyroidectomy may develop hoarseness or may even lose their voice. This happens if the recurrent laryngeal nerve which is located posterior to the trachea, intimately associated with both thyroid lobes, is injured or severed. In the hands of an experienced surgeon, this occurs in <1% of patients who undergo thyroidectomy. And a patient is placed at higher risk for developing this particular complication if the goiter is very large and adherent to its contiguous structures, which is what happens when goiters are left unattended for a very long time. Again, it is best to seek consultation immediately when a goiter or thyroid nodule is noted.

“Bawal magbuhat ng mabigat habang buntis dahil magkaka-Goiter sya.” “Kaya lumalaki ang leeg at nagka-bosyo ang buntis e dahil hindi ito marunong umire.” “Bawal magbuhat ng mabigat habang buntis dahil magkaka-Goiter sya.”

When you have GOITER Visit your doctor or an endocrinologist Blood tests and other tests like ultrasound may be requested for evaluation Medications given should be taken regularly as prescribed

Leilani Mercado-Asis, MD Gabriel Jasul, MD Rosa Allyn G. Sy, MD The Philippine College of Physicians wishes to acknowledge the following for their invaluable efforts in the preparation of this module Nemesio Nicodemus, MD Bien Matawaran, MD Aimee Andag-Silva, MD Leilani Mercado-Asis, MD Gabriel Jasul, MD Rosa Allyn G. Sy, MD Committee on Advocacy & Public Relations Philippine Society of Endocrinology and Metabolism