Final answer:
In an uncontrolled hyperthyroid cat, the hormone concentration changes would show increased levels of thyroxine (T4) along with decreased thyroid-stimulating hormone (TSH) levels due to negative feedback.
Step-by-step explanation:
The hormone concentration changes consistent with an uncontrolled hyperthyroid cat would be increased T4, decreased TSH. Hyperthyroidism is a condition where the thyroid gland is overactive, producing excessive amounts of thyroid hormones. Thyroid-stimulating hormone (TSH), produced by the anterior pituitary gland, controls the release of thyroxine (tetraiodothyronine, T4) and triiodothyronine (T3) from the thyroid gland. In the case of hyperthyroidism, increased levels of T3 and T4 in the blood result in negative feedback on the anterior pituitary, leading to a decrease in the production and secretion of TSH. Therefore, the correct answer is D. Increased T4, decreased TSH.