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What is the cause of secondary hyperthyroidism?
What is the cause of secondary hyperthyroidism?
What is the estimated frequency of HTD in the US?
What is the estimated frequency of HTD in the US?
What is the ratio of women to men affected by Graves disease?
What is the ratio of women to men affected by Graves disease?
What is the prevalence of Graves disease in childhood?
What is the prevalence of Graves disease in childhood?
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What is the age range when Graves disease predominantly affects individuals?
What is the age range when Graves disease predominantly affects individuals?
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What is the term for hyperthyroid disease that produces no symptoms or represents an early stage in the evolution of the disease?
What is the term for hyperthyroid disease that produces no symptoms or represents an early stage in the evolution of the disease?
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What is the frequency of newly diagnosed HTD in pregnancies?
What is the frequency of newly diagnosed HTD in pregnancies?
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What is the age range when the incidence of GD peaks?
What is the age range when the incidence of GD peaks?
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What is the primary mechanism by which antibodies stimulate thyroid follicular cells in Graves disease?
What is the primary mechanism by which antibodies stimulate thyroid follicular cells in Graves disease?
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Which of the following is a complication of chronic HTD?
Which of the following is a complication of chronic HTD?
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What is the most common cause of HTD, accounting for approximately 85% of all cases?
What is the most common cause of HTD, accounting for approximately 85% of all cases?
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What is the term for the sudden availability of large quantities of circulating free/unbound thyroid hormones?
What is the term for the sudden availability of large quantities of circulating free/unbound thyroid hormones?
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Which of the following is a cause of HTD?
Which of the following is a cause of HTD?
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What is the term for the condition that occurs when tumors are solitary and secrete TSH?
What is the term for the condition that occurs when tumors are solitary and secrete TSH?
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What is the second most common cause of HTD in the US overall?
What is the second most common cause of HTD in the US overall?
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What is the term for the condition that occurs when the thyroid gland is tender due to viral infection?
What is the term for the condition that occurs when the thyroid gland is tender due to viral infection?
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What is the primary cause of thyrotoxicosis factitia?
What is the primary cause of thyrotoxicosis factitia?
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Which ovarian tumor can contain thyroid tissue that actively secretes thyroid hormone?
Which ovarian tumor can contain thyroid tissue that actively secretes thyroid hormone?
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What is the most common cause of hypothyroid disease in the United States?
What is the most common cause of hypothyroid disease in the United States?
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What is the primary cause of transient thyrotoxicosis in postpartum thyroiditis?
What is the primary cause of transient thyrotoxicosis in postpartum thyroiditis?
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What is the duration of transient thyrotoxicosis in postpartum thyroiditis?
What is the duration of transient thyrotoxicosis in postpartum thyroiditis?
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What is the primary cause of mild gestational HTD?
What is the primary cause of mild gestational HTD?
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Which type of testicular cancer can cause hyperthyroid disease?
Which type of testicular cancer can cause hyperthyroid disease?
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What is the primary cause of hypothyroid disease following transient thyrotoxicosis in postpartum thyroiditis?
What is the primary cause of hypothyroid disease following transient thyrotoxicosis in postpartum thyroiditis?
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What is the approximate percentage of iodine in amiodarone by weight?
What is the approximate percentage of iodine in amiodarone by weight?
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How long can the half-life of amiodarone be in the human body?
How long can the half-life of amiodarone be in the human body?
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What percentage of patients in the United States develop HTD after taking amiodarone?
What percentage of patients in the United States develop HTD after taking amiodarone?
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How soon can amiodarone-induced HTD occur after initiating therapy?
How soon can amiodarone-induced HTD occur after initiating therapy?
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What is the result of Type II amiodarone-induced HTD?
What is the result of Type II amiodarone-induced HTD?
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How long can thyrotoxicosis last after amiodarone-induced HTD?
How long can thyrotoxicosis last after amiodarone-induced HTD?
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What is a common pathophysiologic mechanism of hyperthyroidism and/or thyrotoxicosis?
What is a common pathophysiologic mechanism of hyperthyroidism and/or thyrotoxicosis?
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What is associated with the hypermetabolic state in hyperthyroidism and/or thyrotoxicosis?
What is associated with the hypermetabolic state in hyperthyroidism and/or thyrotoxicosis?
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What is the result of a thyroid lobectomy operation?
What is the result of a thyroid lobectomy operation?
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What is the most reliable and beneficial laboratory test for diagnosing hyperthyroid disease?
What is the most reliable and beneficial laboratory test for diagnosing hyperthyroid disease?
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What is a common finding on an electrocardiogram of a patient with hyperthyroid disease?
What is a common finding on an electrocardiogram of a patient with hyperthyroid disease?
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What is the effect of smoking on patients with Graves' disease?
What is the effect of smoking on patients with Graves' disease?
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What is the typical finding of serum T3 and T4 levels in patients with hyperthyroid disease?
What is the typical finding of serum T3 and T4 levels in patients with hyperthyroid disease?
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What is the rare exception where serum TSH levels may be high in patients with hyperthyroid disease?
What is the rare exception where serum TSH levels may be high in patients with hyperthyroid disease?
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What is the diagnosis of hyperthyroid disease based on?
What is the diagnosis of hyperthyroid disease based on?
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What is the significance of hypercalcemia in patients with hyperthyroid disease?
What is the significance of hypercalcemia in patients with hyperthyroid disease?
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Study Notes
Types of Hyperthyroidism
- Primary hyperthyroidism: excessive thyroid hormone secretion by the thyroid gland without hypothalamic or pituitary gland stimulation
- Secondary hyperthyroidism: caused by benign tumors of the pituitary gland that secrete thyroid-stimulating hormone (TSH)
- Tertiary hyperthyroidism: typically caused by non-cancerous tumors of the hypothalamus that secrete thyrotropin-releasing hormone (TRH)
Prevalence of Hyperthyroidism
- Estimated frequency in the US: 0.05-1.3%
- Majority of cases are subclinical, with no symptoms or mild symptoms
- Higher prevalence in Caucasian and Hispanic populations compared to African-Americans
- Graves' disease (GD) is more common in women than men, with a ratio of 8:1
- Newly diagnosed HTD occurs in approximately 1 in 2000 pregnancies
Symptoms of Hyperthyroidism
- Muscle weakness, especially in shoulders and thighs
- Frequent and loose bowel movements
- Palpitations, racing, and pounding heartbeat
- Chest pain without coronary artery disease
- Scanty or absent menses (oligomenorrhea and amenorrhea)
- Lack of sexual desire and erectile dysfunction in males
- Inability to concentrate, affecting school or work performance
- Temporary hair loss
- Hypokalemic (low serum potassium concentration)
- Paralysis occurs in approximately 15% of Asian- and Native-American males with HTD
Thyroid Storm
- Rapidly developing, life-threatening complication
- Presents with extreme restlessness, agitation, high body temperature, tachycardia, cardiac arrhythmia, and dehydration
- Caused by sudden availability of large quantities of circulating free/unbound thyroid hormones
- Often occurs with serious infections or extreme stress
Complications of Hyperthyroidism
- Chronic HTD contributes to weak and brittle bones, increasing the risk of osteoporosis
- May result in cardiomyopathy and atrial fibrillation (Afib) in older patients, leading to heart failure
Causes of Hyperthyroidism
- Graves' disease (GD): most common cause, accounting for approximately 85% of cases
- Autoimmune disorder involving the synthesis of antibodies that bind to the TSH receptor
- Other causes include:
- Medications
- Infections
- Cancerous and non-cancerous tumors
- Benign tumors of the thyroid gland (adenomas) that secrete TSH
- Subacute thyroiditis (believed to be caused by viral infection)
- Jod-Basedow disease (iodine-induced HTD)
- Thyrotoxicosis factitia (ingestion of excessive amounts of thyroid hormone)
- Struma ovarii (ovarian tumors containing thyroid tissue that actively secretes thyroid hormone)
Pathophysiology of Hyperthyroidism
- Three basic mechanisms:
- Increased synthesis and secretion of T3 and T4
- Injury to thyroid follicular cells, releasing preformed T3 and T4
- Ingestion of excessive amounts of thyroid hormone or iodine salt-containing preparations
- Hypermetabolic state, increased sympathetic nervous system activity, and increased oxygen consumption and use of metabolic fuels
Diagnosis and Treatment
- Diagnosis: medical history, physical examination, and blood tests (including serum TSH, T3, T4, and FT4 levels)
- Treatment: surgical removal of part of the thyroid gland (subtotal thyroidectomy) or medication to reduce thyroid hormone production
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Description
Learn about the different types of hyperthyroidism, including primary, secondary, and tertiary forms, and their causes. Understand how thyroid hormones are affected and the role of the hypothalamus and pituitary gland.
