Our body maintains an inner temperature that quite constant, usually a few degrees above room temperature. This internal heat is the consequence of our metabolism. Chemical reactions that take place inside our body produce a bit of heat as a result of their activity. Energy is released from molecular unions, and the movement of fluids and organs also tends to slowly raise our temperature.
When our metabolism is slowed down because of a lack of thyroid hormones, our capacity to naturally regulate our temperature can be affected.
People with hypothyroidism can have an increased sensitivity to cold, which means that they suffer from cold more than people around them. Aside from body temperature, other vital signs might drop as well, all as a result of the same deceleration of the metabolic processes. For example, people with hypothyroidism might have a slowed heart rate than average for their level of fitness and activity.