Final answer:
TRH can remain within the normal range in a person with thyroid gland damage due to long-loop negative feedback, which adjusts production of TRH to prevent excessive TSH when the thyroid gland can't respond adequately.
Step-by-step explanation:
In a person with hyposecretion from damage to the thyroid gland, even if the gland is not properly secreting thyroid hormones, TRH can remain within the normal range due to a long-loop negative feedback. This feedback mechanism involves the hypothalamus, the pituitary gland, and the thyroid gland. When the thyroid hormones are low, the hypothalamus continues to release TRH, which prompts the pituitary gland to produce TSH. The thyroid stimulating hormone (TSH) then acts on the thyroid gland, encouraging it to produce more hormones. However, if the thyroid gland is damaged and can't respond adequately, the pituitary gland eventually senses the persistently low thyroid hormone levels and adjusts TRH production to avoid excessive TSH stimulation, which would be futile. This long-loop feedback helps prevent TRH levels from becoming too high, despite the damaged state of the thyroid gland.