A lot of patients are concerned that they might have a thyroid problem. The thyroid’s function can be easily tested, by your doctor, using simple blood levels. Understanding how the thyroid works will help you to understand your blood test results. Thyroid hormone is produced by the thyroid gland and helps to regulate many important functions in the body. Some of the most important functions of thyroid hormone include maintaining hair growth, bowel habits, body temperature, weight and energy levels. The thyroid gland is said to be shaped like a butterfly and is located in the neck just under where you can feel the “Adam’s apple” (both males and females have an Adam’s apple, but it is more noticeable in men). If you feel around your neck, you are not likely to be able to feel your thyroid because it is made up of soft tissue.
The thyroid gland is a factory that makes hormone 24 hours a day. The two thyroid hormones the factory produces are T4 and T3. The thyroid factory makes T4 and T3 “toys” around the clock. The thyroid factory makes much more of the T4 toy than it does the T3. That is because the T4 toy is very durable and lasts a long time even if people play with it. The factory also makes a T3 toy because the T3 toy is super exciting, but it breaks down very easily when it is used. When your doctor orders T4 and T3 blood levels, he is checking to see if the thyroid hormones are adequate in your blood. The T4 test is more reliable over long periods of time (the durable toy). T3 is the active thyroid hormone (the exciting toy) and levels can vary over short periods of time.
The boss of the thyroid factory is the pituitary gland. The pituitary gland is found high up in the body, in the center of the brain. Using our factory example, Mr. Pituitary sits high up in a tower above the factory and calls orders to the factory, telling it to make more or less toys. In your body, the pituitary “calls” the thyroid factory by using a hormone called TSH (“Toy stimulating hormone”).
High Thyroid Hormone Levels:
If the thyroid factory is making a lot T4 and T3 toys, Mr. Pituitary does not need to work hard and he can relax. He makes very few calls to the factory. Someone with high thyroid hormone levels will have a low TSH.
High: T3 and T4
Low Thyroid Hormone Levels:
If the thyroid factory is not making enough T4 and T3 toys, Mr. Pituitary gets upset and calls the factory more often, hoping to ramp up production. In the blood of someone with a low thyroid hormone level, the TSH is high.
Low: T3 and T4
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