1. Everything You Ever Wanted to Know About the Thyroid (but were afraid to ask…)
Caroline Messer, MD
Board Certified Internist, Endocrinologist, and Physician Nutrition Specialist

2. Topics Thyroid Nodules Hyperthyroidism Hypothyroidism
Frequently asked questions dispersed throughout talk

3. Introduction

4. The thyroid is a butterfly-shaped gland in the middle of the neck, located below the larynx (voice box) and above the clavicles (collarbones)
FAQ: If I have an issue with my parathyroid, does this affect my thyroid hormone levels?

5. Thyroid function is controlled by a gland located just below the brain, known as the pituitary.
The pituitary produces thyroid stimulating hormone (TSH), which stimulates the thyroid to produce T3 and T4.
These hormones regulate how the body uses and stores energy.

6. very small changes in serum free T4 concentrations induce very large reciprocal changes in serum TSH concentrations. As a result, thyroid function is best assessed by measuring serum TSH, assuming the absence of pituitary or hypothalamic disease.

7. Thyroid Nodules

8. This figure shows a thyroid nodule on the left side of the thyroid
This figure shows a thyroid nodule on the left side of the thyroid. Thyroid nodules are round or oval-shaped and differ from the surrounding normal thyroid tissue. A person may have one or more thyroid nodules.

9. Thyroid Nodules
Thyroid nodules are very common; up to half of all people have at least one nodule, although most do not know about it
Most nodules don’t change the amount of thyroid hormone in the body, but some cause the thyroid to make too much hormone. These nodules are very rarely cancerous.
FAQ: Can thyroid nodules decrease the amount of thyroid hormone my body is making?

10. Causes of Nodules
Thyroid nodules can be caused many different conditions. Reassuringly, about 95 percent of all thyroid nodules are caused by benign (non-cancerous) conditions.

11. Possible Symptoms
Asymptomatic: found on routine exam or during imaging test performed for another condition
Difficulty swallowing, voice hoarseness, shortness of breath
Symptoms from having too much thyroid hormone

12. Diagnosis
Normal TSH or high TSH: the next step is to have a thyroid ultrasound and fine needle aspiration biopsy (FNA)
Additionally, if TSH is high, thyroid antibodies should be checked to look for Hashimoto’s thyroiditis

13. Diagnosis: Thyroid Ultrasound
Thyroid ultrasound should be performed on all patients with a suspected nodule or nodular goiter on physical examination or with nodules incidentally noted on other imaging studies (carotid ultrasound, CT, MRI or PET scan)
Thyroid ultrasonography is used to answer questions about the size and anatomy of the thyroid and nearby structures in the neck
Findings can be used to select nodules that require FNA biopsy based on size and features

15. Diagnosis: FNA
Thin needle used to remove small tissue samples from the nodule. Samples are examined with a microscope.
FNA biopsy can be performed in the office with a local anesthetic (numbing medicine)
Accurately identifies cancer in a suspicious thyroid nodule. In some cases, the biopsy does not contain enough tissue to make a diagnosis, and surgery is necessary
Results of the biopsy will be one of the following:
Benign (non cancerous)
Malignant (cancer)
Possible or suspicious for malignancy
Non diagnostic or insufficient

17. Diagnosis: Thyroid Scan
Low TSH: the nodule may be producing high levels of thyroid hormone
The next step is to have a thyroid scan to see if the nodules are producing thyroid hormone

18. Thyroid Nodule Diagnosis: Thyroid Scan
Can help determine if a nodule is producing thyroid hormone (i.e., “hot” or “toxic”)
Performed after swallowing a small dose of a radioactive substance
Nodules that absorb the substance are usually not cancerous
Nodules that do not absorb the substance are called “cold,” and have a 5% risk of being cancerous
Nuclear medicine diagnostic procedures have been used for more than five decades, and there are no known long-term adverse effects from such low- dose exposure.
FAQ: Can a thyroid scan itself cause cancer because of the radioactive iodine?

19. Thyroid Scan Results

20. Treatment: Depends on Type of Nodule
Watching & waiting – we don’t always treat nodules right away. We will often repeat yearly thyroid ultrasounds to monitor their size
Radioactive iodine – comes in a pill or liquid that you swallow. Has a small amount of radiation and can destroy a lot of the thyroid gland. Used only to treat nodules that make too much thyroid hormone.
Surgery to remove the thyroid nodule – a procedure to drain fluid from the thyroid nodule, if it is filled with fluid
FAQ: I was placed on synthroid many years ago to shrink the size of my nodule(s). Does this work?

21. Hyperthyroidism

22. What is it?
Hyperthyroidism is the medical term for an overactive thyroid (hyper = excessive)
In people with hyperthyroidism, the thyroid gland produces too much thyroid hormone
When this occurs, the body's metabolism is increased, which can cause a variety of symptoms

23. Symptoms
Anxiety, irritability, trouble sleeping, even psychosis or depression
Weakness (particularly the upper arms and thighs, making it difficult to lift heavy items or climb stairs)
Tremors (of the hands)
Perspiring more than normal, difficulty tolerating hot weather
Rapid or irregular heartbeats

24. Symptoms
Fatigue
Weight loss in spite of a normal or increased appetite
Frequent bowel movements
Some women have irregular menstrual periods or stop having their periods altogether. This can be associated with infertility
Men may develop enlarged or tender breasts, or erectile dysfunction, which resolves when hyperthyroidism is treated

25. Causes: Graves’ Most common cause of hyperthyroidism
Not clear why it develops in most people, although it is more common in certain families
In people with Graves' disease, the immune system produces an antibody that stimulates the thyroid to produce too much thyroid hormone
Most common in women between the ages of , but can occur at any age in men or women

26. The thyroid gland enlarges (called a goiter) and makes excessive amounts of thyroid hormone, causing symptoms of hyperthyroidism
Some people develop eye problems (called Graves' ophthalmopathy), which causes dry, irritated or red eyes, and double vision. Others develop swelling behind the eyes that causes the eyes to bulge out (figure 2), although this is less common. In its most severe form, people with Graves' ophthalmopathy can develop inflammation of the optic nerves, which can result in loss of vision.

27. Hyperthyroidism: Nodules
One or more thyroid nodules (small growths or lumps in the thyroid gland) can produce too much thyroid hormone
The nodule is then called a hot nodule, toxic nodule or toxic nodular goiter

28. Hyperthyroidism: Thyroiditis
Painless ("silent” or “lymphocytic") thyroiditis and postpartum thyroiditis are disorders in which the thyroid becomes temporarily inflamed and releases thyroid hormone into the bloodstream, causing hyperthyroidism
Postpartum thyroiditis can occur several months after delivery. Symptoms may last for several months, often followed by months of hypothyroid symptoms, such as fatigue, muscle cramps, bloating and weight gain
Subacute thyroiditis is thought to be caused by a virus. It causes a painful, tender, enlarged thyroid gland. The thyroid becomes inflamed and releases thyroid hormone into the bloodstream; the hyperthyroidism resolves when the viral infection improves

29. Diagnosis Low TSH, elevated T4 and T3
T3 levels are often disproportionately higher than T4 in hyperthyroidism; T3 measurements may be valuable for evaluating and following patients with this disorder.
Thyroid scan may also be recommended to help determine the cause of hyperthyroidism (Graves' disease, toxic nodular goiter, or thyroiditis)

30. Thyroid Scan Results
E. Thyroiditis

31. Treatment: Anti-Thyroid Drugs
Anti-thyroid drugs, such as methimazole and propylthiouracil, work by decreasing how much thyroid hormone the body makes. Both are very effective, but methimazole is preferred because of a greater risk of serious side effects with PTU
These medications can be used:
As a short term (4-8 weeks) treatment in people with Graves' disease or toxic nodular goiter, before treatment with radioiodine or surgery
As a long term (1-2 years) treatment for Graves' disease. The disease goes into remission in about 30% of people, and anti-thyroid drugs can be used to control hyperthyroidism while waiting to see if remission occurs
People who have very mild Graves' disease may have as high as a 50-70% chance of remission. It is possible to have a relapse years later, and most people will need to eventually consider permanent treatment with radioactive iodine or surgery
Antithyroid drugs have some minor side effects, such as rash, hives, painful joints, fever, and stomach upset. A more serious complication called agranulocytosis (lack of white blood cells) can occur, but this is very rare. PTU has rarely been linked with liver failure.

32. Treatment: Beta- Blockers
Beta-blockers, such as atenolol, are often started as soon as the diagnosis of hyperthyroidism is made
While beta-blockers do not reduce thyroid hormone production, they can control many of the symptoms, such as rapid heart rate, tremors, anxiety and heat intolerance
Once the hyperthyroidism is under control (with anti- thyroid drugs, surgery or radioactive iodine), the beta-blocker is stopped

33. Treatment: Radioactive Iodine
Destroying the thyroid with radiation, called radioiodine ablation, is a permanent way to treat hyperthyroidism
The amount of radiation used is small and does not cause cancer or infertility
Radioiodine is given in liquid or capsule form, and works by destroying much of the thyroid; takes ~6-18 weeks
People with severe symptoms, older adults and people with heart problems should first be treated with an anti- thyroid drug to control symptoms
Most people who take radioiodine develop hypothyroidism and will need to take thyroid hormone supplements for the rest of their lives
As with most treatments, there are some risks with radioactive iodine:
Sometimes, after apparently successful treatment, the condition returns and further treatment is needed.
About 20 percent of people who use radioiodine treatment require a second dose. These people usually have severe hyperthyroidism or a very large goiter.
Occasionally, people with Graves' disease find that their eye symptoms worsen after therapy.
People who are treated with radioiodine should avoid close physical contact, especially with young children and pregnant women, for three to seven days after treatment because of the possibility of exposing them to low doses of radiation. This can be difficult for parents of young children.
You will need to see your doctor or nurse on a regular basis after treatment to have your thyroid hormone levels checked and monitor for hypothyroidism or recurrent hyperthyroidism.

34. Treatment: Surgery
Although surgical removal of the thyroid is a permanent cure for hyperthyroidism, it is used far less often than anti-thyroid drugs or radioactive iodine because of the risks (and expense) associated with thyroid surgery
The risks include damage to the nerves of the voice box and parathyroid glands
However, surgery is recommended when:
A large goiter blocks the airways, making it difficult to breathe.
You cannot tolerate anti-thyroid drugs, and you do not want to use radioiodine
There is a nodule in the thyroid gland that could be cancerous
Most people develop hypothyroidism after surgery and require treatment with thyroid hormone

35. Hypothyroidism

36. What is it?
Hypothyroidism is a condition in which the thyroid gland does not produce enough thyroid hormone
It is the most common thyroid disorder

37. Causes
In ~95% of cases, hypothyroidism is due to a problem in the thyroid gland itself and is called primary hypothyroidism
Rarely, hypothyroidism is a result of decreased production of thyroid-stimulating hormone (TSH) by the pituitary gland
Thyroid problems are more common in women, increase with age and are more common in whites and Mexican Americans than in blacks
However, certain medications and diseases can also decrease thyroid function. As an example, HYPOthyroidism can also develop after medical treatments for HYPERthyroidism, such as thyroidectomy (surgical removal of the thyroid) or radioactive iodine treatment (to destroy thyroid tissue)

38. Symptoms
Thyroid hormone normally stimulates the metabolism, and most of the symptoms of hypothyroidism reflect slowing of metabolic processes. General symptoms may include fatigue, sluggishness, weight gain, and intolerance of cold temperatures.

39. Symptoms
Decreased sweating, thick skin, coarse or thin hair, brittle nails
Mild swelling around the eyes
Slowed heart rate and decreased overall cardiac function leading to fatigue and shortness of breath with exercise
Mild high blood pressure and elevated cholesterol
Tongue swelling, hoarse voice, and sleep apnea
Sleep apnea is a condition in which there is intermittent blockage of the airway while sleeping, causing fitful sleep and daytime sleepiness

40. Symptoms Constipation
Absent or infrequent periods to very frequent and heavy periods
Myxedema coma – in people with severe hypothyroidism, trauma, infection, exposure to the cold and certain medications can rarely trigger a life-threatening condition called myxedema coma, which causes a loss of consciousness and hypothermia (low body temperature)

41. Diagnosis
Blood tests – TSH is the most sensitive test because it can be elevated even with small decreases in thyroid function
Thyroxine (T4), the main product of the thyroid gland, may also be measured to confirm and assess the degree of hypothyroidism
T3 levels are mostly useful in hyperthyroidism. Decreased caloric intake or mild illness can inhibit the conversion of T4 to T3 and lead to transiently low T3 levels. This doesn’t mean that there is a primary thyroid issue.
FAQ: Why aren’t you checking my T3 levels?

42. Treatment
Goal of hypothyroidism treatment is to return blood levels of TSH and T4 to the normal range and to alleviate symptoms
Treatment for hypothyroidism is thyroid hormone replacement therapy, usually given as an oral form of T4
T4 should be taken 1x per day on an empty stomach (1 hour before eating or 2 hours after). Generic (levothyroxine) and brand-name (Synthroid®, Levoxyl®, Levothroid®, Unithyroid®) formulations are equally effective
However, it is preferable to stay on the same type of T4 rather than switch between brand name and/or generic formulations

43. Treatment
If a switch is necessary, a blood test is usually done 6 weeks later to determine if the dose needs to be adjusted. Color-coded tablets can help with dose adjustments.
Some clinicians prescribe another form of thyroid hormone, triiodothyronine (T3) in combination with T4. However, since T4 is converted into T3 in other organs, most studies have not shown an advantage of combination T3 & T4 therapy over T4 alone.
Patients treated with currently available T3-containing preparations have wide fluctuations in serum T3 concentrations throughout the day due to its rapid gastrointestinal absorption and its relatively short half-life in the circulation (about one day).
autoimmune thyroid disease appear to be unusually sensitive to the inhibitory effects of iodide upon its own organification and may fail to escape from the Wolff-Chaikoff effect. Thus, iodide may induce or exacerbate hypothyroidism in patients with Hashimoto's thyroiditis.

44. Treatment
In most cases, symptoms begin to improve within 2 weeks of starting thyroid replacement therapy. However, people with more severe symptoms may require several months of treatment before they fully recover.
FAQ: All the chat sites recommend Armour® thyroid. Why don’t you?
FAQ: Why can’t I treat my hypothyroidism with iodine?
Patients treated with currently available T3-containing preparations have wide fluctuations in serum T3 concentrations throughout the day due to its rapid gastrointestinal absorption and its relatively short half-life in the circulation (about one day).
autoimmune thyroid disease appear to be unusually sensitive to the inhibitory effects of iodide upon its own organification and may fail to escape from the Wolff-Chaikoff effect. Thus, iodide may induce or exacerbate hypothyroidism in patients with Hashimoto's thyroiditis.

45. Q&A Caroline Messer, MD, CCD 914 241-1050 cmesser@mkmg.com