25 Questions
Which of the following best describes the mechanism of thyroid hormone action?
Increasing protein synthesis to stimulate cellular metabolism
What is the primary function of the hypothalamus in regulating thyroid function?
To produce thyrotropin-releasing hormone (TRH) to stimulate the pituitary
Which of the following are results of hyperthyroidism?
Increased appetite and weight loss
What is the primary function of the pituitary in regulating thyroid function?
To release thyroid-stimulating hormone (TSH) to stimulate the thyroid gland
Approximately, what is the percentage of T4 and T3 that is bound to plasma proteins?
99%
What is the result of the outer ring deiodination of T4?
Conversion of T4 to T3
What is the primary function of thyroid hormone T3?
Regulation of metabolic rate and heat production
What is the result of the hydrolysis of thyroglobulin in lysosomal pathway?
Production of free T4 and T3 and iodinated residues
What is the function of thyroid-binding globulin?
To provide a reservoir of hormones with a longer half-life
What is the primary mechanism of action of T3 in the nucleus?
It combines with a nuclear receptor to stimulate transcription of genes for the production of mRNAs
What is the percentage of T3 and T4 that binds to thyroid-binding globulin (TBG) or transthyretin (TTR) in the plasma?
More than 99.5%
What is the mechanism by which T4 is converted to T3 in the cytosol?
Deiodination
What is the percentage of T3 that is released from the thyroid gland?
Around 2-3%
What is the name of the protein that T3 and T4 bind to in the plasma?
Thyroid-binding globulin (TBG) and transthyretin (TTR)
What is the effect of excess TSH on the thyroid gland?
Hypertrophy of the thyroid gland
What is the most common form of hyperthyroidism?
Graves' disease
What is the diagnosis of hyperthyroidism based on?
Low TSH and high T3 and T4
What is the anesthetic concern in hyperthyroidism?
Thyroid storm
What is the preoperative management of hyperthyroidism in emergency surgery?
Propylthiouracil (PTU) and beta blocker
What is the potential complication of goiter during thyroid surgery?
Tracheal deviation
Which of the following is not essential for normal biosynthesis of thyroid hormones?
Ferritin
What is the effect of an increase in plasma levels of TSH alone have on metabolic rate?
It has no effect on the metabolic rate
In which condition is the TSH response to TRH most likely to be reduced?
Hyperthyroidism due to diffuse hyperplasia of thyrotropes
What is the effect of TSH injections on thyroidal uptake of iodine?
It increases the uptake of iodine
Which of the following hormones is least affected by an increase in plasma levels of TRH?
TBG
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