Nearly 5% of the US population has been diagnosed with Hypothyroidism – an underactive thyroid. The thyroid gland is a butterfly-shaped gland located at the front of your neck. The thyroid’s main function is to control metabolism, but it also helps regulate heart rate, breathing, digestion, body temperature, brain development, mental activity, skin/bone maintenance and fertility. Essentially, the thyroid gland affects almost every part of our body!

Symptoms of Hypothyroidism

 If your thyroid gland is underactive, you may experience:

  • Slow or rapid heart rate
  • Weight loss or gain
  • Cold intolerance
  • Depression and anxiety
  • Irregular periods
thyroid tests bend oregon, Inspired Health Center, Bend Oregon

If you have been diagnosed with an underactive thyroid, you are probably familiar with getting thyroid labs done and taking thyroid medication to manage your condition. In the world of thyroid function, the conversion of free T4 (thyroxine) to free T3 (triiodothyronine) is a crucial process. Free T3 is the active form of thyroid hormone that plays a vital role in regulating metabolism, energy production, and overall body functions. However, there are various factors that can impede this conversion process, leading to difficulty optimizing your thyroid levels and this can impact how you feel. Let’s discuss the most common factors.

Factors that Affect the Conversion of Free T4 to Free T3

Nutrient Deficiencies

First off, conversion of Free T4 to Free T3 requires certain nutrients, such as selenium and zinc. Deficiencies in these essential minerals can hinder the conversion process, as the enzymes involved in the conversion require these nutrients as cofactors. Therefore, inadequate intake or absorption of these nutrients can impair the conversion and result in low free T3 levels. Thyroid Renew is an excellent support for this issue by providing the nutrients and herbs needed to support the conversion of free T4 to free T3.


Chronic stress, whether physical or emotional, can disrupt the conversion of free T4 to free T3. Stress activates the hypothalamic-pituitary-adrenal (HPA) axis, which can lead to elevated cortisol levels. High cortisol levels can inhibit the conversion process and decrease the production of free T3. Additionally, stress-induced inflammation can also interfere with the conversion process. Adapt + is a wonderful supplement designed support our body in times of stress.

Estrogen Dominance

Hormonal imbalance, especially Estrogen dominance, can increase levels of a protein called thyroid-binding globulin (TBG), which binds to thyroid hormones and reduces their availability for conversion.

Liver Dysfunction

The conversion of free T4 to free T3 primarily occurs in the liver. Therefore, any liver dysfunction or impairment can negatively affect the conversion process. Liver diseases, alcohol abuse, and certain medications can disrupt the liver’s ability to efficiently convert T4 to T3, leading to imbalances in thyroid hormone levels. Detox Rebalance is a potent option to support liver detoxification.

The conversion of free T4 to free T3 is a complex process that can be influenced by several factors. If you suspect any issues with your thyroid function, it is important to consult with a healthcare provider for proper evaluation and treatment.

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[2] “Thyroid.” 2022.
[3] “The effects of zinc and selenium co-supplementation..” 2023.
[4] “Thyroid hormone regulation by stress…” 2011.
[5] “Role of estrogen in thyroid function and growth.” 2011.
[6] “Metabolism of thyroid hormone.” 2017.