Question

Which of the following is true of primary hypothyroidism?

Multiple Choice

In primary hypothyroidism, there is an increase in the production of total T4 and T3.

In primary hypothyroidism, there is an increased level of circulating thyroid-stimulating hormone (TSH).

In primary hypothyroidism, the thyroid gland is not stimulated by TSH.

Primary hypothyroidism is caused by the malfunction of the pituitary gland.

Answer 1

In primary hypothyroidism, there is an increased level of circulating thyroid-stimulating hormone (TSH) due to the thyroid gland's inability to produce sufficient amounts of hormones T4 and T3, despite the pituitary gland's response to stimulate it.

Step-by-step explanation:

The correct answer to the question "Which of the following is true of primary hypothyroidism?" is that in primary hypothyroidism, there is an increased level of circulating thyroid-stimulating hormone (TSH). Primary hypothyroidism occurs when the thyroid gland itself is not capable of producing sufficient amounts of thyroid hormones, thyroxine (T4) and triiodothyronine (T3).

In response to low levels of T3 and T4, the pituitary gland increases the secretion of TSH to stimulate the thyroid gland to produce more hormones. Over time, if the thyroid gland remains unresponsive—possibly due to damage, autoimmune disease like Hashimoto's thyroiditis, or other conditions—the levels of TSH continue to rise, making the increased TSH characteristic of primary hypothyroidism.

It is not accurate to say that TSH does not stimulate the thyroid gland in primary hypothyroidism; rather, the thyroid gland is not responding properly to stimulation by TSH. Also, primary hypothyroidism is not caused by a malfunction of the pituitary gland; that would be secondary hypothyroidism. Lastly, there is no increase in the production of total T4 and T3 in primary hypothyroidism; the condition actually involves a decrease in these crucial hormones.