The Thyroid-Adrenal Connection

Your hormones (and their associated glands) do not exist in a vacuum.

I see many patients suffering from hypothyroidism who do not feel better on standard thyroid treatments (even integrative treatments). The medication has been tuned perfectly and the lab values are right where they should be. The gut flora has been rebalanced, inflammatory foods have been eliminated, nutrients have been restored. And you still feel like crap. You still struggle to get out of bed every morning and your energy still crashes in the afternoon. Why?

Your hormones do not exist in a vacuum.

Likewise, I see a lot of patients who have been diagnosed with adrenal dysfunction who have taken the supplements for months, who have practiced meditation so much, they couldn't be anymore zen. And yet you still need at least 10 hours of sleep to feel even remotely human in the morning and your digestion is still off. Why?

Your hormones do not exist in a vacuum.

The hormones from your thyroid interact with the hormones from your adrenal gland. The hormones from your adrenal gland impact the way your thyroid functions. They exist in a balance. When one is out of balance, the other usually follows. So often to restore balance to the thyroid, we have to restore balance to the adrenal glands first. Or vice versa.

The Thyroid-Adrenal Connection

High cortisol suppresses TSH production.

TSH is a messenger from the brain that tells the thyroid to make more thyroid hormone (check out this article for more info about how the thyroid works). So when TSH decreases, this results in less thyroid hormone. 

Your body makes excess cortisol in response to a stressor. Historically, these stressors may have been threats to our survival. And even though our stressors have changed in modern times, we can still experience this threat response with deadlines at work, confrontations with family, or traffic. The goal of the threat response is to run away from the threat. So the threat response will shut down bodily functions that do not help us run away such as digestion, reproductive function, and even thyroid hormone production. 

Stress inhibits the conversion of T4 to T3.

Physiological stress (cold exposure, starvation, excessive physical activity, blood sugar imbalances, excessive inflammation) and emotional stress can inhibit the enzyme that converts T4 to T3. T4 is an inactive form of thyroid hormone, while T3 is the active form. The conversion of T4 to T3 happens throughout the body. When our body cannot convert T4 to T3, it will drive the conversion of T4 to reverse T3, which is inactive and cannot be activated. Reverse T3 also inhibits the conversion of T4 to T3, just compounding the issue. So basically, stress interferes with our thyroid hormones causing a functional thyroid hormone deficiency. 

Stress can lead to thyroid hormone resistance.

The stress response often leads to increased levels of inflammatory molecules, called cytokines. Studies have shown that this inflammation can make your cells less responsive to thyroid hormones. So even though you are on the correct medication dose and your labs are perfect, your body is not able to respond to your medication. So you still lack energy, you still suffer from brain fog, and you just don't feel like yourself.

Thyroid hormone levels may alter the secretion and metabolism of cortisol.

In the Thyroid-Adrenal connection, most of the focus is on how cortisol affects the thyroid. But there is evidence that this is a two way street. Studies have shown a correlation between thyroid hormones and how our body makes and metabolizes cortisol. When thyroid hormones are low, the adrenal gland does not secrete as much cortisol and that cortisol is metabolized much slower. So if you have been focusing on treating your adrenal glands with little success, it may be time to investigate your thyroid.

Testing Your Thyroid

If you ask your doctor to assess your thyroid, most likely they will just test TSH. Which isn't good enough to fully understand your physiology. Here are the thyroid tests I recommend:

  • TSH
  • Free T4
  • Free T3
  • Reverse T3
  • Anti-TPO (antibodies)
  • Anti-TG (antibodies)

Most people feel best when their TSH is between 1 and 2, though the reference ranges suggest that up to 8 is normal. If your TSH is above 3 and you have symptoms of hypothyroidism, this suggests some level of thyroid dysfunction. Elevated antibodies indicate that what is really going on is an autoimmune disease, called Hashimoto's. High reverse T3 suggests a peripheral thyroid hormone dysfunction and the next step is to evaluate your adrenal glands.

Testing Your Adrenal Glands

There are several ways to test your adrenal gland function:

  • Serum cortisol, typically only tested once in the morning
  • Salivary cortisol tested at 4 time points in one day
  • Urinary cortisol and metabolites tested at 3-4 time points

Your cortisol levels fluctuate normally throughout the day and sometimes, there is dysfunction present only at certain times of the day. This is why I do not recommend using serum cortisol.

Salivary cortisol is better because it tests throughout the day, but it is still only accessing free cortisol, which is about 1-3% of total cortisol production. So this test does not necessarily reflect accurate physiology.

This is why I recommend urinary cortisol and metabolites as the test of choice. Assessing the metabolites provides a more accurate assessment of total cortisol production. Looking at the metabolites also gives us a more accurate picture of the active cortisol in your body. In my practice, I use the DUTCH test by Precision Analytics to assess cortisol and cortisol metabolites.

Assessing and treating your thyroid and adrenal glands can be complicated and take time. It is not as simple as taking this supplement and eating that diet. This is why I recommend working with a doctor who knows what they are doing. Unfortunately, most conventionally trained doctors do not assess the thyroid correctly and know next to nothing about the adrenal glands. So find a licensed naturopathic doctor to work with. In the meantime, you can read more articles about the adrenal glands and thyroid by clicking on a link to the right of the page (or bottom if you are viewing on a mobile device).


  5. Chopra IJ, Chopra U, Smith SR, et al. Reciprocal changes in serum concentrations of 3,3’,5-triiodothyronine (T3) in systemic illnesses. J Clin Endocrinol Metab 1975;41:1043–9.
  6. Chopra IJ, Williams DE, Orgiazzi J, Solomon DH. Opposite effects of dexamethasone on serum concentrations of 3,3_,5_- triiodothyronine (reverse T3) and 3,3_,5-triiodothyronine (T3). J Clin Endocrinol Metab 1975;41:911–920.