As we age the thyroid gland, like all the endocrine glands, produces lower levels of thyroid hormones. Because the “normal laboratory range” of thyroid hormones is based upon a population normal, 90%-95% of all individuals will have thyroid levels that fall within the “normal range”. But many people whose thyroid hormone levels fall within the so called “normal” range do not feel normal or healthy. Young healthy individuals have thyroid hormone levels which are high in the “normal range”. Older, less healthy individuals have thyroid hormone levels which are in the lower end of the “normal range”. Over your lifetime your thyroid hormone levels call fall by 50%, with you experiencing a 50% decline in your energy level, yet your thyroid hormone level will remain in the laboratory “normal range”, the low end of the “normal range”, yet still in the “normal range”. Despite the fact that you may have a host of symptoms of hypothyroidism, due to your decline in thyroid hormone production with age, your doctor will tell you that you are in the “normal range”. But you are not feeling normal because your thyroid hormones have declined as you have aged. You do not want your thyroid hormones to be in the “low normal range”, rather you want to keep your thyroid hormone levels in the “optimum range” so that you have good energy and feel healthy.