thermoregulation and thyroid hormone disorders

Last reviewed 10/2023

The thyroid gland is intimately related to thermoregulation as T4 and T3 influence the basal metabolic rate in all cells.

Hence, in hyperthyroidism, temperature rises because:

• the basal metabolic rate is raised
• there is increased oxygen consumption
• the patient is hyperactive
• adrenal function is globally enhanced

Hence, body temperature is raised relative to the desired set point; the sufferer feels hot and does not like warm environments. Compensation takes the normal form of vasodilatation and sweating, giving the classical symptoms of clammy, warm skin.

The exact reverse is true for hypothyroidism: an inability to elevate core temperature to the desired set point leaves the sufferer cold and unhappy in cold environments.

Severe hyperthyroidism and the thyrotoxic crisis are both extensions to the thermostatic physiological mechanism present in simple hyperthyroidism. However, hyperpyrexia is a more likely complication.