What effect does thyroid hormone have on the metabolism?

Thyroid hormone plays a crucial role in regulating metabolism by increasing the metabolic rate of various tissues in the body. It does this primarily through several mechanisms, including enhancing the basal metabolic rate (BMR), which refers to the rate at which the body expends energy at rest.

Thyroid hormones, particularly thyroxine (T4) and triiodothyronine (T3), stimulate the production of enzymes involved in metabolic processes, enhance oxygen consumption, and increase the turnover of macronutrients, such as carbohydrates and fats. This leads to a rise in energy expenditure and promotes catabolism of fats and carbohydrates for energy usage.

Moreover, thyroid hormone also increases the activity of sodium-potassium ATPase, which contributes to the elevated metabolic rate by increasing heat production (thermogenesis), and facilitates the growth and development of different tissues. Given these mechanisms, the primary effect of thyroid hormone on metabolism is indeed an increase in the overall metabolic rate.