How much do thyroid levels fluctuate day to day?

The thyroid, a small gland at the base of your neck (just beneath the Adam’s apple, and shaped like a butterfly), is responsible for the production of two very important hormones in the body: triiodothyronine (T3) and thyroxine.

Get your thyroid examined, especially if you are experiencing problems with your body temperature (you’re too cold or too hot) or your body isn’t using fats and carbohydrates as fast as it should (you’re packing on weight), because it controls these functions and others. Normal thyroid levels are between .03 to 3--and while levels can fluctuate greatly over time--they do not do so enough to warrant measuring them on a day-to-day or same day basis.

Thyroid hormones and how they are produced

There are two thyroid hormones: triiodothryonine (T3) and thyroxine (T4), but there is also a thyroid stimulating hormone (TSH). The pituitary is responsible for the creation of TSH and even has special cells for its production. The hypothalamus regulates the pituitary to produce TSH. The pituitary, along with the hypothalamus, also controls the production of the other two hormones and sends all three of them out into the body to perform various important functions, such as regulating your heart rate.

Level fluctuation process and dangers

The hypothalamus dictates the request for TSH in the body by sending a signal to the pituitary. The pituitary determines the exact amount of TSH needed by the levels of T3 and T4 already in the blood; therefore, any fluctuation of either of these three hormone levels in the body by other influences (medicines or health problems), can cause the hypothalamus and the pituitary to create and release too much or too little of these important hormones. This creates some thyroid level fluctuations and possible problems with fat processing, body temperature maintenance and the regulation of your heartbeat.

Reasons for fluctuating levels

There are many reasons your thyroid levels may fluctuate: stress; illness; certain prescription drugs such as antidepressants); being pregnant; season changes; consuming too much of certain foods such as soy, cabbage, kale, turnips; beginning/stopping the use of iron, vitamins or high-fibre foods; birth control pill dosage timing; and changes in the potency of current thyroid medications.

Day-to-day fluctuation of levels

Since fluctuating thyroid levels can give you an irregular heart beat, disrupt your body temperature and cause you to pack on more fat, it is important to know just how likely these thyroid levels are to fluctuate on a daily basis--and what prompts such a fluctuation, if it occurs. According to, there is no reason to be concerned about possible day-to-day thyroid fluctuations, since thyroid hormones T3, T4 and TSH do not fluctuate much throughout any one day--or even day-to-day. In addition, thyroid blood testing is a highly reliable indicator of any abnormality (or lack of one) with the thyroid.


Even though a day-to-day, recognisable fluctuation in thyroid levels is not likely, advise your doctor of any medication or lifestyle changes, especially if an abnormally high (or low) level comes back on a thyroid test when you have one done.