ENDOCRINE ORGANS AND RESPIRATORY SYSTEM
THYROID
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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1%
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99%
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75%
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25%
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Detailed explanation-1: -Approximately 99.97% of circulating T4 and 99.7% of circulating T3 are bound to these proteins.
Detailed explanation-2: -These proteins are estimated to transport roughly 3% of the total T4 and perhaps as much as 6% of the total T3 in serum.
Detailed explanation-3: -Thyroid hormones are poorly soluble in water, and more than 99% of the T3 and T4 circulating in blood is bound to carrier proteins. The principle carrier of thyroid hormones is thyroxine-binding globulin, a glycoprotein synthesized in the liver.
Detailed explanation-4: -Others are thyroid binding prealbumin and albumin. TBG, an inter-alpha-globulin, has the highest affinity for the iodothyronines, but because of its low concentration, it has a limited capacity. Both T4 and T3 are tightly bound; T4 is only 0.03% free, while T3 is 0.3% free.
Detailed explanation-5: -Thyroxine-binding globulin (TBG) binds most T3/T4 in the blood.