Now, we have two important abnormalities that we should be familiar with when we're discussing T three and T four. We have something called hypothyroidism, and we have hyperthyroidism. So hypo simply means we have an insufficiency of. So that means our thyroid gland isn't able to actually produce a sufficient quantity of T three T four for one reason or another. And this basically means that the cellular respiration rate will be low. So we're not going to have enough energy.