Which description accurately reflects thyroid hormones' influence on energy expenditure?

Which description accurately reflects thyroid hormones' influence on energy expenditure?

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

Answer: (B)

Thyroid hormones raise energy expenditure by boosting resting metabolic rate and generating more heat. They do this by increasing the transcription of metabolic enzymes and mitochondrial activity, leading to higher oxygen use and ATP turnover. They also raise activity of Na+/K+ ATPase, which uses energy and contributes to heat production, and they promote thermogenesis, especially in brown fat. The overall effect is a higher basal metabolic rate, more heat produced, and greater total energy expenditure. That’s why the description that includes increased basal metabolic rate, heat production, and energy expenditure fits best. A statement of no change or a decrease would contradict the known stimulatory effect of thyroid hormones, and claiming energy expenditure only would miss the important increases in resting metabolic rate and heat production.

Thyroid hormones raise energy expenditure by boosting resting metabolic rate and generating more heat. They do this by increasing the transcription of metabolic enzymes and mitochondrial activity, leading to higher oxygen use and ATP turnover. They also raise activity of Na+/K+ ATPase, which uses energy and contributes to heat production, and they promote thermogenesis, especially in brown fat. The overall effect is a higher basal metabolic rate, more heat produced, and greater total energy expenditure.

That’s why the description that includes increased basal metabolic rate, heat production, and energy expenditure fits best. A statement of no change or a decrease would contradict the known stimulatory effect of thyroid hormones, and claiming energy expenditure only would miss the important increases in resting metabolic rate and heat production.