Hyperthyroidism

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May 30, 2019
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Hyperthyroidism (Thyrotoxicosis)

Essentials of Diagnosis

  • Nervousness, weight loss with increased appetite, heat intolerance, increased sweating, muscular weakness and fatigue, increased bowel frequency, polyuria, menstrual irregularities, infertility.
  • Goiter, tachycardia, atrial fibrillation, warm moist skin, thyroid thrill and bruit, cardiac flow murmur; gynecomastia.
  • Eye signs: stare, lid lag, exophthalmos.
  • TSH low or absent; TSI, iodine uptake, T3, and T4 increased; T3 suppression test abnormal (failure to suppress radioiodine uptake).

General Considerations

Hyperthyroidism is caused by the increased secretion of thyroid hormone (Graves' disease, Plummer's disease, iodine [jodbasedow], amiodarone toxicity, TSH-secreting pituitary tumors, hCG-secreting tumors) or by other disorders that increase thyroid hormone levels without increasing thyroid gland secretion (factitious hyperthyroidism, subacute thyroiditis, struma ovarii, and, rarely, metastatic thyroid cancers that secrete excess thyroid hormone). The most common causes of hyperthyroidism are diffusely hypersecretory goiter (Graves' disease) and nodular toxic goiter (Plummer's disease).

In all forms, the symptoms of hyperthyroidism are due to increased levels of thyroid hormone in the blood stream. The clinical manifestations of thyrotoxicosis may be subtle or marked and tend to go through periods of exacerbation and remission. Some patients ultimately develop hypothyroidism spontaneously or as a result of treatment. Graves' disease is an autoimmune disease—often with a familial predisposition—whereas the etiology of Plummer's disease is unknown. Most cases of hyperthyroidism are easily diagnosed on the basis of the signs and symptoms; others—eg, mild or apathetic hyperthyroidism—which occurs most commonly in the elderly—may be recognized only with laboratory testing for a suppressed TSH level.

Thyrotoxicosis has been described with a normal T4 concentration, normal or elevated radioiodine uptake, and normal protein binding, but with increased serum T3 by RIA (T 3 toxicosis). T 4 pseudothyrotoxicosis is occasionally seen in critically ill patients and is characterized by increased levels of T4 and decreased levels of T3 due to failure to convert T4 to T3. Thyrotoxicosis associated with toxic nodular goiter is usually less severe than that associated with Graves' disease and is only rarely if ever associated with the extrathyroidal manifestations of Graves' disease such as exophthalmos, pretibial myxedema, thyroid acropathy, or periodic hypocalcemic paralysis.

If left untreated, thyrotoxicosis causes progressive and profound catabolic disturbances and cardiac damage. Death may occur in thyroid storm or because of heart failure or severe cachexia.

Diagnostic algorithm for thyrotoxicosis. MNG = multinodular goiter; RAI = radioactive iodine; TSH = thyroid-stimulating hormone.

Board Review Questions

1. Choose the one best response to this question. Which of the following is not a manifestation or associated condition with Graves hyperthyroidism?

A. diffuse goiter

B. ophthalmopathy

C. localized dermopathy

D. diffuse arthropathy

E. Addison's disease

2. Choose the one best response to this question.

Where does the arterial supply to the superior and inferior parathyroids originate from?

A. superior thyroid artery

B. inferior thyroid artery

C. external carotid artery

D. internal carotid artery

E. common carotid artery

3. Choose the one best response to this question. A 56-year-old female is found to have symptoms of hypothyroidism with a painless, enlarged, firm, rubbery thyroid gland. FNA shows diffuse infiltration of the gland with lymphocytes and plasma cells. Which of the following best describes her condition?

A. Hashimoto's thyroiditis

B. acute suppurative thyroiditis

C. Riedel's thyroiditis

D. painless thyroiditis

E. subacute de Quervain thyroiditis

Answers

1. The correct answer is D. diffuse arthropathy.

2. The correct answer is B. inferior thyroid artery. 

3. The correct answer is A. Hashimoto's thyroiditis. 


Read more about Hyperthyroidism on AccessSurgery in Schwartz's Principles of Surgery

Go to the profile of Gerard Doherty

Gerard Doherty

Moseley Professor of Surgery, Harvard Medical School, Surgeon-in-Chief, Brigham Health & Dana-Farber Cancer Institute

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