Thyroid Parameters

Front 1

Generally, a 52 year old female is noted to have a low free T4 levels. She has a high TSH and elevated thyroid peroxidase antibodies. What would be a very likely diagnosis?

Back 1

Hypothyroidism associated with Hashimoto's disease.

Front 2

Is hypothyroidism a common condition?

Back 2

It is very common, especially in women over 50.

Front 3

What is primary hypothyroidism/

Back 3

Primary hypothyroidism is an autoimmune disease in which increased levels of thyroid peroxidase antibodies attack thyroid peroxidase(TPO).

Front 4

What is TPO?

Back 4

TPO is an enzyme found in thyroid follicle cells that iodinates T4 and T3. Inflammation is usually the result as thyroid peroxidase is destroyed. The thyroid gland is damaged.

Front 5

What is the cause of Hashimoto's disease?

Back 5

Its cause is unclear. It is however, 5-10X more common in women than men. Its cause in males is even less clear.
There may be a genetic predisposition, or due to declining estrogen levels with menopause. Environmental factors may play a role in its development.

Front 6

Is hashimoto's disease sometimes found with other autoimmune diseases?

Back 6

Yes. It tends to be more common in families that have other autoimmune diseases, such as type 1 diabetes and Celiac disease.

Front 7

Hypothyroidism is often associated with elevated LDL cholesterol levels. True/False

Back 7

True.

Front 8

What is secondary hypothyroidism?

Back 8

Secondary hypothyroidism is caused by an inadequate release of of thyroid stimulating hormone (TSH) from the pituitary gland.

Front 9

Are there other autoimmune diseases of the thyroid gland?

Back 9

Yes. Hashimoto's thyroiditis, atrophic thyroiditis, and postpartum thyroiditis are all autoimmune diseases of the thyroid. All forms of thyroid autoimmunity typically start with T and B cells:

Front 10

Why exactly is Hashimoto's considered an autoimmune condition?

Back 10

In cases of autoimmunity, T cells are tricked into classifying molecules on the body's own cells as invaders. In such cases, B cells then produce antibodies, called autoantibodies, which attack those cells.

Front 11

Has an immunologic similarity been suggested for both Hashimoto's disease and Grave's disease?

Back 11

One theory proposes that Hashimoto's thyroiditis and Graves' disease (a form of hyperthyroidism) are caused by a similar immunologic dysfunction. Similar immune system substances called antibodies are present in both diseases, and some researchers believe that the predominance of one or another antibody determines which of the diseases become manifest. The two diseases, then, are essentially two sides of a single coin.

Front 12

What is Atrophic thyroiditis?

Back 12

Atrophic thyroiditis is similar to Hashimoto's thyroiditis, except a goiter is not present.

Front 13

What is Riedel's thyroiditis?

Back 13

Riedel's thyroiditis is a rare autoimmune disorder, in which scar tissue progresses in the thyroid until it produces a hard stony mass that suggests cancer. Hypothyroidism develops as the scar tissue replaces healthy tissue. Surgery is usually required, although early stages may be treated with corticosteroids or other immunosuppressive drugs.

Front 14

What is Subacute thyroiditis?

Back 14

Subacute thyroiditis is a temporary condition that passes through three phases: hyperthyroidism, hypothyroidism, and a return to normal thyroid levels. Patients may have symptoms of both hyperthyroidism and hypothyroidism (such as rapid heartbeat, nervousness, and weight loss), and they can feel extremely sick. Symptoms last about 6 - 8 weeks and then resolve in most patients, although each form carries some risk for becoming chronic. Subacute thyroiditis appears to be responsible for about 10% of all cases of hypothyroidism.

Front 15

What is Painless Postpartum Subacute Thyroiditis?

Back 15

Postpartum thyroiditis is an autoimmune condition that occurs in up to 10% of pregnant women and tends to develop between 4 - 12 months after delivery. In most cases, a woman develops a small, painless goiter. It is generally self-limiting and requires no therapy unless the hypothyroid phase is prolonged. If so, therapy may be thyroxine replacement for a few months. A doctor will prescribe beta-blockers if the hyperthyroid phase needs treatment. Some evidence suggests that half of women with this condition develop permanent hypothyroidism within 7 years. Women who have had recurrent episodes after previous pregnancies and women who have other autoimmune disorders are at higher risk for this form of subacute thyroiditis.

Front 16

What is Painless, sporadic or silent thyroiditis?

Back 16

Painless Sporadic, or Silent, Thyroiditis. This painless condition is very similar to postpartum thyroiditis except it can occur in both men and women and at any age. About 20% of patients with silent thyroiditis may develop chronic hypothyroidism. Treatment considerations are the same as for postpartum subacute thyroiditis.

Front 17

What is Granulomatous thyroiditis?

Back 17

Painful, or Granulomatous, Thyroiditis. This condition comes on suddenly with flu-like symptoms and severe neck pain and swelling. It generally occurs in the summer and is five times more common in women. It recurs in about 2% of patients. Hypothyroidism persists in about 5%. Treatments typically include pain relievers and, in severe cases, corticosteroids.

Front 18

What are some common symptoms of hypothyroidism?

Back 18

Fatigue, dry skin, intolerance to cold, thinning hair, weight gain, constipation.

Front 19

How is Hashimoto's disease often treated?

Back 19

It is treated with replacement hormone therapy such as Levothyroxine (Synthroid). Low doses are recommended with slow incremental increases, until T4 and TSH levels attain normal levels.

Front 20

Are there risks in the treatment of hypothyroidism?

Back 20

Yes. Treatment of hypothyroidism increases the risk of osteoporosis.
Too much thyroid hormone causes osteoclastic bone resorption and can decrease intestinal calcium absorption. Occasionally, calcium and vitamin D supplementation is recommended.

Front 21

is it OK to take a calcium supplement with levothyroxine?

Back 21

No. The calcium and the levothyroxine should be taken at least 4 hours apart. This is because divalent minerals such as calcium, iron and magnesium can impair the absorption of the thyroid medication.

Front 22

Is there an association between thyroid disease and iodide abnormalities?

Back 22

Yes. Too much or too little iodide can cause hypothyroidism. If there is a deficiency of iodide, the body cannot manufacture thyroxine. About 200 million people around the world have hypothyroidism because of insufficient iodine in their diets. Too much iodide is a signal to inhibit the conversion process of thyroxine to T3. The end result in both cases is inadequate production of thyroid hormones. Some evidence suggests that excess iodine triggers the process leading to Hashimoto's thyroiditis.

Front 23

Are there other drugs that can affect thyroid function levels?

Back 23

Yes. Lithium. Lithium, a drug widely used to treat psychiatric disorders, has multiple effects on thyroid hormone synthesis and secretion. Up to 50% of patients who take lithium develop a goiter, with 20% developing symptomatic hypothyroidism, and another 20 - 30% developing hypothyroidism without symptoms.
Amiodarone. The drug amiodarone (Cordarone), which is used to treat abnormal heart rhythms, contains high levels of iodine and can induce hyper- or hypothyroidism, particularly in patients with existing thyroid problems. Hypothyroidism occurs in 20% of patients and is the more common effect in the U.S. and other countries where dietary iodine is abundant. Hyperthyroidism is a less common effect in these regions.

Front 24

Can chemotherapeutic drugs influence thyroid levels?

Back 24

Yes. Drugs used for treating epilepsy, such as phenytoin and carbamazepine, can reduce thyroid levels. Certain antidepressants may cause hypothyroidism, although this is rare. Interferons and interleukins are used for treating hepatitis, multiple sclerosis, and other conditions. Evidence suggests that these drugs increase antibodies that put patients at risk for hypo- or hyperthyroidism. Some drugs used in cancer chemotherapy, such as sunitinib (Sunent) or imatinib (Gleevec), can also cause or worsen hypothyroidism.
Radiation Therapy. High-dose radiation for cancers of the head or neck and for Hodgkin's disease can also cause hypothyroidism in up to 65% of patients within 10 years after treatment.