TSH is a hormone released by the pituitary gland that has the role of controlling the thyroid’s thyroxine T4 and triiodothyronine T3 production. T3 and T4 are released into the body by the thyroid gland, and everything that’s happening in the body is connected to existing balance between these two hormones.
TSH levels can fluctuate due to a lot of reasons including genetics, being pregnant, how much iodine it’s consumed, inflammation and the T3 and T4 levels. When these two hormones are low, the production of TSH rises, and when they’re high, TSH decreases.
A healthy person has a level of TSH between 0.4 and 4.0 mIU/L, although some doctors and researchers say that it shouldn’t be bigger than 2.5. For someone between the ages of 20 and 54, TSH should be between 04 and 4.2. For those who are older than 55, the range changes to 0.5-8.9 mIU/L.
For children, the TSH level must be between 1 and 39 (younger than four days), between 1.7 and 9 for babies who have 2 to 20 weeks of age, and for those who are older than 21 weeks but younger than 20 years, the TSH levels must vary between 0.7 and 64 mIU/L.
For pregnant women things get a little more complicated, considering that the TSH levels are different for every trimester of pregnancy. For the first one the TSH levels must be between 0.3 and 4.5, for the second one between 0.3 and 4.6, and for the third trimester of pregnancy, TSH can vary between 0.8 and 5.2 mIU/L.
Level > 4.0 mIU/L
If your level of TSH is higher than 4.0, it means that your thyroid gland isn’t producing enough hormones. This means that treatment should be concentrated on replacing the missing hormones with medication.
TSH level < 4.0 mIU/L
If the TSH level is too low, then the thyroid is producing too many hormones. It’s best to avoid iodine, and you should decrease the intake of synthetic hormone treatment.
But is the reading of TSH enough?
TSH is the main marker doctors use in order to establish if a person has health issues or not. But recent studies have shown that there can be cases where the level of TSH and the levels of T3 and T4 don’t work by the previously mentioned rules, leading to a lot of misdiagnoses. Even stress can modify TSH in healthy individuals.