Why are total thyroxine (T4) levels increased in pregnant women and in women taking oral contraceptives?

Unlock all questions

This demo includes only 20 questions. Upgrade to access hundreds of questions, flashcards, exam simulations, and disable ads.

Full question bankExam simulationsFlashcards
From $24.99Unlock all

Enhance your knowledge with the Ciulla Clinical Chemistry Test. Study with interactive quizzes, featuring flashcards and multiple-choice questions. Each question offers hints and explanations for better understanding. Prepare effectively and excel in your exam!

Multiple Choice

Why are total thyroxine (T4) levels increased in pregnant women and in women taking oral contraceptives?

Explanation:
The key idea is that total T4 rises when the amount of thyroid-binding protein in the blood increases. During pregnancy and with estrogen-containing oral contraceptives, the liver makes more thyroxine-binding globulin (TBG). With more TBG available, more T4 becomes bound, so the total T4 measured in serum goes up. The free T4, which is the active portion, remains normal because the body regulates it tightly. So the change in concentration of thyroxine-binding globulin best explains the increase in total T4.

The key idea is that total T4 rises when the amount of thyroid-binding protein in the blood increases. During pregnancy and with estrogen-containing oral contraceptives, the liver makes more thyroxine-binding globulin (TBG). With more TBG available, more T4 becomes bound, so the total T4 measured in serum goes up. The free T4, which is the active portion, remains normal because the body regulates it tightly. So the change in concentration of thyroxine-binding globulin best explains the increase in total T4.

More Multiple Choice Questions
Subscribe

Get the latest from Examzify

You can unsubscribe at any time. Read our privacy policy