Disorders of the Thyroid Flashcards by Katie Keller

Inflammation of the thyroid

Multiple causes and forms

Acute and subacute forms

Thyroiditis

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What is the most common thyroid disorder in the United States?

Hashimoto Thyroiditis

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Most common thyroid disorder in the United States

Autoimmune condition

Often progresses to hypothyroidism

More common in white females

Familial trend

Hashimoto Thyroiditis

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What are some comorbidities that are also associated with Hashimoto thyroiditis?

DM type 1
Autoimmune gonadal failure
Hypoparathyroidism
Adrenal insufficiency

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What are some risk factors for Hashimoto thyroiditis?

More common in smokers
Family history
Common in Hepatitis C
Drug induced
Head-neck radiation exposure

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What levels are usually elevated in Hashimoto thyroiditis?

Serum anti-thyroperoxidase and anti-thyroglobulin antibody levels

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1/3 of patients with Hashimoto thyroiditis may also have what other autoimmune condition?

Sjogren Syndrome

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15% of Hashimoto thyroiditis patients also have serum antibodies associated with what disease?

celiac disease

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Autoimmune thyroiditis

Occurs in 7.2% of women after delivery

Fetal cells in maternal thyroid

Most common in women with high thyroid peroxidase in first trimester or after delivery

Painless Postpartum Thyroiditis

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What are the signs and symptoms of painless postpartum thyroiditis?

Hyperthyroidism 1-6 months after delivery, lasts about 1-2 months

Hypothyroidism 4-8 months after delivery

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Subacute form of Hashimoto’s thyroiditis

Similar to painless postpartum thyroiditis, but not related to pregnancy

Painless Sporadic Thyroiditis

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Also called de Quervain, granulomatous, or giant cell thyroiditis

Presumed to be caused by a viral infection or a postviral inflammatory process (Usually follows an URI)

Peak incidence in summer

Young and middle aged women (Most often occurs at 40-50 years of age)

Subacute Thyroiditis

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What is the hallmark presentation of subacute thyroiditis?

Anterior localized neck pain, with or without fever

Thyroid gland is always tender on exam

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How is subacute thyroiditis diagnosed?

Imaging:

Radioactive iodine uptake will show low uptake or a faint heterogeneous pattern of radionuclide uptake during the hyperthyroid phase

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What is the first line treatment in subacute thyroiditis?

ASA/NSAIDs to relieve pain and inflammation

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Rare

Non-viral infection of the thyroid gland (Usually bacterial)

Patients with pre-existing thyroid disease

Suppurative Thyroiditis

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Rarest form

Normal thyroid tissue is replaced with connective tissue = fibrosis

Can extend deep into the neck causing the thyroid to become attached with the neck

Cause is unknown, butusually manifestation of multifocal systemic fibrosis syndrome

Reidel Thyroiditis

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What are the signs/symptoms of Reidel thyroiditis?

Asymmetric enlargement

Stony hard and adhere to neck structures

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What is the treatment of choice for Reidel thyroiditis?

Treatment of choice is Tamoxifen

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dramatic enlargement of the thyroid gland

goiter

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Large retrosternal goiters can cause venous distension over the neck and difficulty breathing, especially when the arms are raised. This is called what?

Pemberton’s Sign

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Encompasses a heterogeneous group of disorders:

Grave’s disease

Toxic multinodular goiter (TMNG)

Toxic adenoma (TA)

Hyperthyroidism

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What is the most common cause of hyperthyroidism and thyrotoxicosis?

Grave’s Disease

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Autoimmune disorder associated with diffuses thyroid enlargement, excessive secretion of thyroid hormone, and antibodies against the thyroid

Females > males (8:1)

Young to middle-aged

Enlarged thymus and elevated ANA

Exophthalmos

Grave’s Disease

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What is a risk factor for Graves disease, especially for ophthalmopathy

Smoking

Painless lumps composed of edematous subcutaneous tissue and thickening of overlying skin on lower legs Resembles the skin of an orange and is thickened and rough, erythematous

Graves Dermopathy - pretibial myxedema

What percentage of Grave's patients have ophthalmopathy manifestations/symptoms?

25%

List some causes of hyperthyroidism

Grave's disease Toxic adenomas Subacute (de Quervain) thyroiditis Factitial thyrotoxicosis Hashimoto’s thyroiditis Amiodarone Pituitary Adenoma Struma ovarii

Found in 3% of dermoid ovarian tumors Means goiter of the ovary that contains mostly thyroid tissue leading to hyperthyroidism Most are benign, however can be malignant in a small percentages in cases

Struma ovarii

What is the best test for thyrotoxicosis?

TSH

Provides a life-sized picture of thyroid uptake Also useful for detecting metastatic thyroid cancer

Radioiodine Scans

Helpful in patients who have palpable thyroid nodules

Ultrasound

Methods of choice for scanning orbits in Graves ophthalmopathy when extraocular muscles are involved Severe exophthalmos

MRI/CT

Initial treatment of choice in thyroid storm

Propranolol

Medication class that inhibits thyroid hormone formation in the gland

Thiourea Drugs

Excellent method of destroying overactive thyroid tissue Treatment of choice for a “hot nodule” or Grave’s disease Do NOT give in pregnant women

Radioactive iodine ¹³¹I

Triggered by stressful illness, thyroid surgery, or RAI Underlying cause is commonly Grave’s disease or TMNG Manifestations – typically have an exaggeration of the usual symptoms of hyperthyroidism

Thyroid Storm (Crisis)

What is the initial treatment of choice in a thyroid storm and why?

Propranolol 🡪 cardio protectant

Common disorder Affects 1% of the general population 🡪 5% older than 60 20% in the elderly 3x higher in women than in men Has an effect on most body functions

Hypothyroidism

What is the most common cause of hypothyroidism?

Hashimotos thyroiditis

List some causes of hypothyroidism

Hashimoto’s thyroiditis Older age Amiodarone Hepatitis C Chemotherapy

Anti-arrhythmic with a high iodine content

Amiodarone

Single best screening test for hypothyroidism is what lab?

TSH

Abnormal thyroid function tests 🡪 low T4 and FT4 Do not have thyroid disease Severe illness, caloric deprivation, major surgery

Euthyroid Sick Syndrome

List some complications of hypothyroidism

Cardiac (Pre-existent CAD and CHF) Bacterial pneumonia Megacolon Myxedema Myxedema madness

Infiltration of skin by mucopolysaccharides Giving a waxy or coarsened appearance

Myxedema (complication of hypothyroidism)

Organic psychosis with paranoid delusions

Myxedema madness (complication of hypothyroidism)

What is the drug of choice in the treatment of hypothyroidism?

Levothyroxine

Severe, life-threatening hypothyroidism Medical emergency!! Mortality rate is high if you don’t catch it Most often seen in elderly women

Myxedema Crisis

List some causes of the myxedema crisis

CVA Stop taking thyroxine Underlying infection Cardiac illness Respiratory illness CNS illness Cold exposure Drug use

Second most common pediatric endocrine disease

Hypothyroidism

Condition of severely stunted physical growth and mental growth due to untreated congenital deficiency of thyroid hormones Usually due to maternal hypothyroidism

Cretinism

What tests mandatory when you find a nodule?

Thyroid function tests

In thyroid nodules, do single or multiple nodules carry a higher risk of progression to thyroid cancer?

Neither - Same overall risk of thyroid cancer

Large substernal goiter Facial erythema JVD Progresses to cyanosis and facial edema when arms are raised above head (Pemberton sign)

Superior Vena Cava Syndrome

What is the preferred imaging in evaluation of thyroid nodules?

Neck ultrasound - Preferred over CT/MRI

What symptoms accompanying a thyroid nodule are concerning for cancer?

Hoarseness Vocal cord paralysis Large nodule Adhere to trachea or strap muscles Lymphadenopathy History of radiation

Hyperfunctioning nodules are rarely what?

malignant

What lab needs to be obtained in all patients with a thyroid nodule?

TSH

On a neck ultrasound, a nodule having these features are at an increased likelihood of malignancy

Irregular or indistinct margins Heterogenous nodule echogenicity Intranodular vascular changes Microcalcifications Complex cyst Diameter > 1cm

Best method to assess thyroid nodule for malignancy

Fine Needle Aspiration Biopsy

Most accurate and cost-effective method for evaluating thyroid nodules

Fine Needle Aspiration Biopsy

Malignant nodules on FNA biopsy warrant what type of treatment?

Total Thyroidectomy

Surgery is limited in the treatment of benign thyroid nodules. List some reasons why a patient would be a surgical candidate with benign nodules

Indeterminant or suspicious cytology Compression syndromes Discomfort Cosmetic embarrassment

Radioiodine therapy is used in patients with thyroid nodules with what?

Hyperthyroid patients with toxic thyroid adenomas, multinodular goiter, or Graves disease

Presents as painless swelling in region of the thyroid Majority present with an asymptomatic nodule on the thyroid Increased incidence with age (most common after age 30) More common in females; 3:1 Aggressiveness increases significantly in older patients Thyroid function tests usually normal

Thyroid Neoplasia and Cancer

What are some risk factors for thyroid carcinoma?

History of childhood head and neck irradiation and/or total body radiation for bone marrow transplantation Family history of thyroid carcinoma or thyroid cancer syndrome (multiple endocrine neoplasia 2) in a first-degree relative Nodules - Rapidly growing, Hoarseness, Fixation of nodule to surround tissue Associated cervical lymphadenopathy

What are the four types of thyroid carcinomas?

Papillary Follicular Medullary Anaplastic

Which type of thyroid carcinoma is described below? Most common – 80% Less aggressive Confined to thyroid and regional lymph nodes Overall cure rate very high 🡪 near 100% for small lesions in young patients Exposure to head and neck radiation

Papillary

What is the most common type of thyroid carcinoma?

Papillary

Which type of thyroid carcinoma is described below? Second most common – 14% More aggressive than papillary carcinoma Slightly older age group than papillary (less common in children) Invasion into vascular structures (veins and arteries) within the thyroid gland is common Age is a very important factor in terms of prognosis Occurs rarely after radiation therapy

Follicular

What is the second most common type of thyroid carcinoma?

Follicular

Which type of thyroid carcinoma is described below? 3% of cases Associated with MEN 2 Originates from parafollicular cells (C cells) Secretes peptides Regional metastasis occurs early 🡪 cervical lymph nodes Distant metastases occurs late 🡪 liver, bone, brain, and adrenal medulla Not associated with radiation exposure Initial presentation – 30% - Flushing and diarrhea (carcinoid symptoms)

Medullary

Which type of thyroid carcinoma is described below? Rarest – 3% Most aggressive thyroid cancer Extremely poor prognosis Usually presents in older patient (rare in young patients) May arise many years (~20) following radiation exposure Cervical metastasis is present in the vast majority (over 90%) of cases at the time of diagnosis (survival at 3 years is less than 10%)

Anaplastic

Which type of thyroid cancer has the best prognosis?

Papillary

Which type of thyroid cancer has the worst prognosis?

Anaplastic

Which two types of thyroid cancer are associated with radiation exposure?

Papillary Anaplastic

Which two types of thyroid cancer are not associated with radiation exposure?

Follicular Medullary

What is the MOST important treatment variable influencing prognosis in thyroid cancer?

Adequate surgery (thyroidectomy)

List some adjunctive therapies that may be utilized in treating thyroid cancer

Radioactive iodine treatment TSH suppression External beam irradiation