Thyroid Hormones and Their Functions

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Questions and Answers

What is one of the key roles of thyroid hormones in the body?

Increasing water retention

Controlling blood sugar levels

Stimulating muscle growth

Regulating oxygen uptake (correct)

Which step in the synthesis of thyroid hormones involves the incorporation of iodine?

Release of hormones from colloid

Organification of iodine (correct)

Iodide uptake

Formation of T3 and T4

What condition is characterized by inadequate secretion of thyroid hormones?

Cretinism

Thyrotoxicosis

Hypothyroidism (correct)

Hyperthyroidism

Which drug is commonly used for the treatment of hypothyroidism?

Levothyroxin (C) Signup and view all the answers

Hyperthyroidism is more prevalent in which demographic?

Young women (B) Signup and view all the answers

What is the most common cause of hyperthyroidism?

Graves disease (A) Signup and view all the answers

Which medication is specifically used for myxedema coma?

Liothyronine (C) Signup and view all the answers

What effect do thyroid hormones have when combined with antidiabetic drugs?

Enhance hypoglycemic effects (B) Signup and view all the answers

What is the ratio of T4 to T3 in Liotrix?

4:1 (C) Signup and view all the answers

Which treatment is considered the primary option for thyroid malignancy?

Surgery (C) Signup and view all the answers

What is a potential risk associated with the use of Orlistat in patients with thyroid hormone therapy?

Hypothyroidism (A) Signup and view all the answers

What mechanism does alpha lipoic acid have on thyroid hormones?

Interferes with the conversion of T4 to T3 (C) Signup and view all the answers

Which side effect is NOT commonly associated with thioamides?

Hypertension (D) Signup and view all the answers

What should be done when propyl thiouracil is taken with digoxin?

Reduce the dose of digoxin (A) Signup and view all the answers

Why might adjuncts like ionic inhibitors be used in thyroid hormone treatment?

To compete with iodide uptake (A) Signup and view all the answers

Which of the following is true regarding rifampin's effect on thyroid hormones?

It may increase the metabolism of thyroid hormones (B) Signup and view all the answers

In what situation are thioamides commonly used?

In mild cases of thyrotoxicosis (D) Signup and view all the answers

Which of the following side effects is associated with thioamides?

Joint pain (A) Signup and view all the answers

Study Notes

Thyroid Hormone Action

Thyroid hormones are crucial for physical, mental, and sexual development.
They influence oxygen consumption and metabolic rate.
They play a role in glucose absorption, utilization, and heart rate.
They also affect cholesterol and glycogen deposition.

Thyroid Hormone Synthesis

Iodide uptake is the first step.
Organification of iodine involves incorporating it into iodine.
Iodine combines with tyrosine to form MIT (monoiodotyrosine) and DIT (diiodotyrosine).
MIT and DIT combine to create T3 and T4.
These hormones are stored in colloid and released by a protease enzyme.
The process is controlled by TSH, regulated by feedback mechanisms.

Hypothyroidism

Insufficient thyroid hormone secretion.
Treatment involves levothyroxine (T4) or liothyronine (T3).
Thyroid hormones can interact with cholestyramine, estrogens, oral contraceptives, and antidiabetic drugs.
Alpha lipoic acid can also affect thyroid hormone conversion.

Hyperthyroidism

Excessive thyroid hormone production.
Characterized by increased metabolism in tissues.
More common in females.
Graves' disease is a major cause.
Autoimmune disorder affecting thyroid receptors.
Medications, like thioamides (e.g., propylthiouracil, carbimazole), are used for treatment.
Surgery might be necessary in certain cases.

Thioamides Interactions

Some thioamides (like propylthiouracil) interact with warfarin, affecting vitamin K function.
Thioamides can increase serum digoxin levels, potentially causing cardiac arrhythmias.

Radioactive Iodine

Concentrates in thyroid glands, destroying follicles.
Used in hyperthyroidism treatment (after other methods fail).
Long-term effects may include hypothyroidism.

Iodine Inhibitors

Substances like perchlorate and thiocyanate compete with iodide uptake.
Lugol's iodine or potassium iodide can inhibit TSH action and reduce gland size and vascularity.

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Description

Explore the essential roles of thyroid hormones in the body, including their impact on development, metabolism, and heart rate. Understand the synthesis process of T3 and T4, as well as the implications of hypothyroidism and its treatments. This quiz will test your knowledge on these critical hormones.