Thyroid hormones (T3 and T4) have regulatory roles in all of the following EXCEPT:
Thyroid hormones are responsible for maintaining the normal hypoxic and hypercapnic drive in the respiratory center of the brain, and regulate gastrointestinal motility which leads to diarrhea in hyperthyroidism and constipation in hypothyroidism. They also regulate bone and protein turnover and the speed of muscle contraction and regulation, hepatic gluconeogenesis, cholesterol synthesis, and intestinal glucose absorption.
In North America, hyperthyroidism is most often caused by:
Graves disease, named after Robert Graves, the Irish physician who described the disorder in three patients in 1835, is the most common cause of hyperthyroidism in North America, and accounts for 60 to 80% of cases.
Subtotal or total thyroidectomy is preferred for the treatment of Graves disease:
Subtotal or total thyroidectomy is now preferred over subtotal thyroidectomy due to a lower recurrence rate. Surgery is preferred over medical therapy (radioactive iodine) in childbearing women who desire to have children in the near future, in noncompliant patients, or when airway obstruction appears likely.
What is the recommended course of action when fine needle aspiration biopsy (FNAB) of a thyroid nodule is "follicular neoplasm?"
Follicular neoplasms of the thyroid are less aggressive than papillary neoplasms, and a fine needle aspiration biopsy (FNAB) may be unable to differentiate between a follicular adenoma and a follicular carcinoma. For this reason unilateral lobectomy is recommended for this FNAB diagnosis.
Which diseases are associated with germline mutations in the RET tyrosine kinase receptor gene?
Mutations in the extracellular domain of the RET tyrosine kinase receptor are associated with multiple endocrine neoplasia type 2A (MEN2A), familial medullary thyroid cancer (FMTC), and Hirschsprung disease. Mutations in the intracellular domain are associated with MEN2B, FMTC, and Hirschsprung disease.
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