Chekoff, a young intern working in the lab of Jan Wolff at the NIH in the mid 60

Question

Chekoff, a young intern working in the lab of Jan Wolff at the NIH in the mid 60's, found that high circulating levels of iodine have a paradoxical effect on thyroid function: it blocks thyroid hormone synthesis and release (this is now called the Chekoff-Wolff effect). This is important clinically because many antiseptics are iodine-based (e.g., betadine). It is still not uncommon that post-surgical treatment includes frequent and liberal application of these antiseptics for extended duration (this is especially problematic in infants).

What measurements would you make to determine that such a patient has reduced thyroid hormone levels in serum?

What measurements would you make to determine that the problem is with the thyroid gland? (explain your reasoning)

Describe what happens to thyroid hormones once they leave the thyroid gland, including how they act on target cells.

Explanation / Answer

Answer-1- we should measure the level of T3,T4 and TSH to determine the pathology of thyroid.

Answer-2-TSH levels should be done first,as it is most sensitive test.

In hypothyroidism,the level of tsh is increased and levels of T3 and T4 decreases.

In hyperparathyroidism,the level of TSH is decreased and levels of T3 and T4 increases.

Answer-3-action of thyroid hormones-

Thyroid Hormone Receptors and Mechanism of Action

Receptors for thyroid hormones are intracellular DNA-binding proteins that function as hormone-responsive transcription factors, very similar conceptually to the receptors for steroid hormones.

Thyroid hormones enter cells through membrane transporter proteins. A number of plasma membrane transporters have been identified, some of which require ATP hydrolysis; the relative importance of different carrier systems is not yet clear and may differ among tissues. Once inside the nucleus, the hormone binds its receptor, and the hormone-receptor complex interacts with specific sequences of DNA in the promoters of responsive genes. The effect of the hormone-receptor complex binding to DNA is to modulate gene expression, either by stimulating or inhibiting transcription of specific genes.

Related Questions

Navigate

• Browse (All)
• Browse C
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.