Which metabolic change is most directly attributed to thyroid hormones?

Which metabolic change is most directly attributed to thyroid hormones?

• A. Decrease basal metabolic rate, heat production, and energy expenditure.
• B. Increase basal metabolic rate, heat production, and energy expenditure.
• C. Increase energy expenditure only.
• D. No change in basal metabolic rate, heat production, or energy expenditure.

Answer: (B)

Thyroid hormones push the body's overall metabolism to run faster and generate more heat. T3 and T4 act on cellular machinery to increase the rate at which cells burn fuel, boost mitochondrial activity, and raise Na+/K+-ATPase activity, all of which raise energy use even at rest. They also make tissues more responsive to catecholamines, which further amplifies metabolic rate. The net effect is higher basal metabolic rate, more heat produced as a byproduct of increased metabolism, and greater total energy expenditure. That’s why the correct description includes increases in basal metabolic rate, heat production, and energy expenditure. If you consider the other possibilities, they don’t fit because thyroid hormones do not decrease metabolism, nor do they leave metabolic activity unchanged. Saying energy expenditure increases alone would miss the substantial rise in resting heat production and basal metabolic processes.

Thyroid hormones push the body's overall metabolism to run faster and generate more heat. T3 and T4 act on cellular machinery to increase the rate at which cells burn fuel, boost mitochondrial activity, and raise Na+/K+-ATPase activity, all of which raise energy use even at rest. They also make tissues more responsive to catecholamines, which further amplifies metabolic rate. The net effect is higher basal metabolic rate, more heat produced as a byproduct of increased metabolism, and greater total energy expenditure. That’s why the correct description includes increases in basal metabolic rate, heat production, and energy expenditure.

If you consider the other possibilities, they don’t fit because thyroid hormones do not decrease metabolism, nor do they leave metabolic activity unchanged. Saying energy expenditure increases alone would miss the substantial rise in resting heat production and basal metabolic processes.