Question

In chronically deficient patients, this abnormality is directly related to the enlargement of the thyroid gland
A. Impaired conversion of T3 and T4
B. Reduced activity of thyroperoxidase
C. Elevated levels of TSH
D. An antibody that binds to the TSH receptor in the thyroid gland

Answer 1

Hint:
Before choosing the correct option, we should know about the thyroid gland.
The thyroid gland generally contains the enzyme thyroid peroxidase (TPO). In the synthesis of thyroid hormones, TPO is crucial. Antibodies to TPO are found in the blood via a TPO test. You may have Hashimoto's disease if your tests reveal elevated levels of antibodies against thyroid peroxidase or thyroglobulin. The chemical reaction that adds iodine to the protein thyroglobulin, a crucial step in the production of thyroid hormones, is aided by thyroid peroxidase. The rate of chemical processes in the body as well as growth and brain development are significantly regulated by thyroid hormones (metabolism).

Complete answer:
An autoimmune disease, which develops when your immune system mistakenly attacks your body rather than defending it, is the most frequent cause, or "attacker." The "goitre belt" was the name of this region. The thyroid gland is enlarged in a goitre. When a person does not consume enough iodine, it occurs.
So, the abnormality of enlargement of the thyroid gland is the elevated levels of TSH.

Option ‘C’ is correct

Note:
Thyroid stimulating hormone is referred to as TSH. A blood test called a TSH test is used to measure this hormone. TSH readings that are abnormally high or low could indicate a thyroid issue. The thyroid is a little gland at the front of your neck that resembles a butterfly. Thyroxine levels that are low and TSH levels that high signify underactive thyroid function. That's because your pituitary creates more TSH to encourage the production of more thyroid hormone by your thyroid gland.