We see a lot of people that suffer from one or more symptoms attributed to an under-functioning thyroid. Many of these people are on medications to boost thyroid hormone (T4 and/or T3), but find that their underlying symptoms – including fatigue, hair loss/thinning, dry skin or constipation – don’t improve. The reason could be that they are not actually addressing the underlying cause(s) of the thyroid dysfunction; one of those underlying causes is likely adrenal fatigue.
How the Adrenals Affect Thyroid Function
Most people think of the adrenals solely in regards to stress and the “fight-or-flight” response that is so often discussed. But the effects of ongoing adrenal stimulation reach far beyond how we react to stress. In fact, continual adrenal stimulation, due to prolonged stress, can have a major impact on almost all organs and tissues in the body. In particular, several hormones involved with adrenal stimulation can directly and indirectly inhibit proper thyroid function.
When our body encounters a stress – whether it by physical (like an injury), psychological (like worry or fear) or physiological (like an illness or disease) – the adrenal glands help us prepare to deal with the stress. In order to understand how this relates to thyroid function, we have to delve into the biochemistry of the stress response (just a little:))
On a biochemical level, a stress is first recognized by a gland in your brain called the hypothalamus that secretes a hormone called “corticotropin releasing hormone” (CRH) that instructs another gland – called the pituitary – to send a signal to the adrenals to make chemicals that will prepare us to deal with whatever the stress is. One of these chemicals is called cortisol, which helps us mobilize our physical and mental reserves to deal with the stress at hand. These responses are designed to be short-lived, which means our bodies are designed to deal with stress and then return to a normal, relaxed state.
However, in our modern world, stressors come at us from all angles, all the time. When this happens, the hypothalamus continues to send out more CRH ultimately telling the thyroid to produce more cortisol. In addition to helping us deal with stress, these two chemicals – CRH and cortisol – also impact thyroid function.
CRH causes indirect inhibition of thyroid stimulating hormone (TSH) at the pituitary level. This means that CRH inhibits the thyroid from working properly. In addition, research indicates that high levels of cortisol have an inhibitory effect on the enzyme that converts T4 to T3 (called 5-deiodinase); T3 is the more active thyroid hormone, which is responsible for most of the effects that we attribute to thyroid function. Once more, research shows that cortisol favors the conversion of T4 to rT3, which is a storage form of the hormone. This means that cortisol decreases the amount of T3 that is available to promote a health metabolism, and may help explain why people that take thyroid medications like Synthroid or levothyroxine (which contain only T4) often find minimal or no relief of symptoms; if they have not properly addressed adrenal fatigue, the T4 from the medication is not being converted into T3 efficiently, which is why their symptoms persist. In addition, excess cortisol has also been shown to inhibit TSH production by the pituitary.
There are a couple key takeaways from this. First, anyone that has a hypo-thyroid issue MUST address and properly support adrenal function in order to have any chance of re-establishing proper thyroid function. This may involve dietary and lifestyle change as well as supplemental support. Second, anyone taking medication for hypothyroidism that is not getting relief from symptoms should also turn to proper adrenal support as a possible solution. Adrenal fatigue is notoriously hard to correct, so working with a skilled provider will certainly help. Even with proper adrenal support, it is not uncommon for it to take 3-9 months until you begin to see a change in thyroid function. Lastly, if you suffer from an under-functioning thyroid, make sure that you get more tests done than just a TSH. We recommend the following at a minimum: TSH, Free T3 and Free T4 ( it would be ideal to add reverse T3 (rT3) as well); Adrenocortex Profile (https://gdx.net/product/adrenocortex-stress-hormone-test-saliva) and 25-hydroxy vitamin D.
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- Khun ER, Geris KL, van der Geyten S, et al. Inhibition and activation of the thyroidal axis by the adrenal axis in vertebrates. Comp Biochem Physiol 1998;120(1):169-74.