Are your thyroid hormones reaching your cells?

Once your thyroid gland produced thyroid hormones, these hormones must reach its end destination: the cells in your body.

Think about it this way: the thyroid hormones must catch a ride on a bus to get to its destination.  There are plenty of busses to make sure that this happens.  

The bus is actually called TBG (thyroxine-binding globulin), and it is a protein in your blood.  The thyroid hormones attaches to TBG, and then it gets transported throughout your body.  

The level of TBG (think about the number of buses available) should be just right – not too few, not too many.  If there are too few busses, the thyroid hormones cannot get on the bus to get to the cells.  If there too many busses, the thyroid hormones can get on the bus, but it cannot get off the bus and get to the cells.  

So can experience hypothyroid symptoms even if your thyroid is making enough hormones.  

What can cause changes in TBG levels?

TBG levels may be low due to acute illness, chronic liver disease, malnutrition, stress from surgery, and medications (such as androgens – like testosterone, salicylates, l-asparaginase and large doses of glucocorticoids).

TBG levels may be too high due to hypothyroidism, liver disease, pregnancy and oral contraceptives.  

Test your sex hormones

When you do your thyroid blood tests, it is also key to test for your sex hormones (testosterone, progesterone and estrogen).  When your sex hormone levels are not right, it can impact the level of the TBG in your blood.