★ Must-know
📌 Hyperthyroidism is characterized by decreased TSH with increased free T4 and free T3, whereas hypothyroidism is characterized by increased TSH with decreased free T4 and free T3.
Further detail
Hypothyroidism can result from iodine deficiency, destruction of the gland by surgery, irradiation or thyroiditis, or disorders of hormone synthesis.
Hyperthyroidism can result from:
Hypothyroidism lowers T3/T4, whereas hyperthyroidism raises T3/T4.
1. Which laboratory pattern most strongly indicates primary hyperthyroidism?
2. Which combination correctly describes major functions of the thyroid gland?
3. Which statement best distinguishes iodine-123 from iodine-131 in thyroid imaging and treatment?
Which hormones does the thyroid secrete?
The thyroid secretes T3 and T4.
What are the main functions of thyroid hormones?
They regulate energy metabolism, growth, thermogenesis, and body weight.
How is hyperthyroidism characterized in terms of TSH and thyroid hormones?
By decreased TSH and increased free T4 and free T3.
How is hypothyroidism characterized in terms of TSH and thyroid hormones?
By increased TSH and decreased free T4 and free T3.
Name a cause of hypothyroidism related to iodine.
Iodine deficiency can cause hypothyroidism.
What gland-related causes can lead to hypothyroidism?
Destruction of the gland by surgery, irradiation, or thyroiditis can cause hypothyroidism.
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