Thyroid Hormone Deficiency: Signs and Solutions

Have you ever felt like you’re walking through life in slow motion? Like the spark you once had has dimmed and you’re dragging your body through the day despite getting a full night’s sleep? Maybe your clothes don’t fit quite the same, even though your diet hasn’t changed. Or perhaps you just don’t feel like yourself anymore. If this sounds familiar, your thyroid might be whispering for help.

As a functional medicine physician, I’ve seen it time and again: people being told everything is “normal” when their symptoms scream otherwise. Thyroid hormone deficiency—or what some refer to as hypothyroidism—can sneak up quietly and disguise itself as everything from aging and depression to laziness and burnout. It affects millions, especially women, and yet it’s so often dismissed.

What Are the Signs of Thyroid Hormone Deficiency?

Let’s start with the thyroid hormone deficiency symptoms that are often brushed off as “just life.”

• Fatigue that doesn’t lift with rest
• Weight gain or inability to lose weight despite doing all the right things
• Hair thinning or loss, including eyebrows
• Cold intolerance (everyone else is comfortable, but you’re bundled in layers)
• Constipation, dry skin, and puffiness
• Low mood, anxiety, depression or brain fog
• Menstrual irregularities or fertility issues

I’ve had patients who’ve been told they just need to exercise more, sleep more, or take an antidepressant. But you can’t out-jog, out-diet, or out-meditate a sluggish thyroid.

Why the Standard Tests Miss the Mark

Traditional medicine often relies solely on TSH (Thyroid Stimulating Hormone) to assess thyroid function. But that’s just one piece of the puzzle. I look deeper—free T3, free T4, reverse T3, and thyroid antibodies—because your thyroid isn’t just about numbers. It’s about how you feel.

A “normal” TSH doesn’t mean you’re thriving. Optimal is not the same as normal. And that’s where the functional medicine lens becomes powerful—we connect your story, your symptoms, and your labs in a way that brings clarity.

What’s New or Overlooked?

What’s emerging now is an understanding of how cellular hypothyroidism—where thyroid hormone doesn’t get into the cells efficiently—can exist even when labs look “fine.”¹ High stress, chronic inflammation, nutrient deficiencies (like selenium, zinc, and iron), and high reverse T3 can block thyroid hormone activity at the cellular level.

Gereben and colleagues emphasized how local tissue regulation of thyroid hormone through deiodinases (enzymes that activate or deactivate thyroid hormone) plays a pivotal role. For example, inflammation or illness can trigger the enzyme D3, which inactivates thyroid hormone right inside the cell—even if blood levels look normal. That means someone can experience all the symptoms of deficiency without it ever showing up on a basic lab panel.

Key Takeaways from the Study:

• Thyroid hormone activity is tissue-specific and not always reflected in blood tests.
• Inflammation, stress, and nutrient deficiencies can trigger enzymes that block thyroid hormone action.
• Chronic illness or even aging can reduce active T3 at the cellular level, leading to functional deficiency.

Practical Solutions You Can Start Today

1. Get a full thyroid panel. Don’t settle for TSH alone. Ask for free T3, free T4, reverse T3, and TPO/TG antibodies (anti thyroid peroxidase and anti thyroglobulin) to get the full picture.
2. Replace thyroid hormone if deficient. If you have low thyroid hormone levels, or even “normal” levels, but you’re still symptomatic, talk to your physician about low thyroid hormone treatment. If you’re on levothyroxine (T4) alone and still not feeling well, discuss adding liothyronine (T3). A 2022 study found that “relatively lower FT3 concentrations, even within the normal reference range, were related to impaired quality of life in Hashimoto’s thyroiditis patients treated with LT4″—supporting the value of FT3 in clinical decisions. ²
3. Support your adrenals. Chronic stress elevates cortisol, which suppresses T3. Ground yourself with restorative practices like breathwork, prayer, stillness, and gratitude journaling.
4. Nourish your thyroid. Eat foods rich in iodine (sea vegetables), selenium (Brazil nuts), zinc (pumpkin seeds), and tyrosine (turkey, chicken, eggs), but be cautious. While these nutrients are essential, excessive iodine or selenium can damage thyroid tissue and worsen autoimmune activity. ³ Always measure your levels before supplementing. While iodine deficiency is widely recognized, most people don’t realize that too much iodine or selenium can also be harmful. Excessive iodine intake has been associated with increased risk of thyroiditis, hypothyroidism, and even hyperthyroidism, particularly in individuals with underlying thyroid disease. ⁴ There is less of a risk of toxicity from foods. Many supplements may have too much, 
5. Reduce inflammation triggers. Gluten, dairy, and processed foods can fire up immune responses, especially in autoimmune thyroid disease. Consider an elimination diet and tune into what your body is telling you.
6. Limit thyroid-disrupting toxins. Fluoride, BPA, and heavy metals can interfere with thyroid function. Filter your water, avoid plastic containers, and choose clean, nontoxic personal care products.
7. Incorporate supportive lifestyle habits. Sleep, stress management, movement, and circadian rhythm alignment all influence thyroid hormone levels and conversion. According to research, lifestyle factors can impact thyroid function at multiple levels—from hormone synthesis to metabolism.⁵
8. Work with someone who listens. Your symptoms matter. You deserve care that sees the whole you—not just your lab values. Apply for a no obligation clarity call to see if we are a good fit. 

You’re Not Crazy. You’re Not Lazy. You’re Not Broken.

One of the most healing things I’ve witnessed in practice is the moment a patient feels seen. When I explain how everything they’ve been feeling has a name, a pattern, a reason—it’s like watching someone finally exhale after holding their breath for years.

Thyroid hormone deficiency is not your fault. It’s not all in your head. It’s something we can test, understand, and treat in a way that honors your body and its wisdom.

You don’t have to keep pushing through. There’s a path forward, and I’d be honored to walk it with you.

1. Functional Medicine
2. HCG Diet
3. HRT for Women
4. Functional Medicine Blog

References:

1. Gereben B, Zavacki AM, Ribich S, et al. Cellular and Molecular Basis of Deiodinase-Regulated Thyroid Hormone Signaling. Endocr Rev. 2008;29(7):898-938. doi:10.1210/er.2008-0019
2. Cui Z, Ding X, Bian N, et al. Relatively Lower FT3 Levels Are Associated with Impaired Quality of Life in Levothyroxine-Treated Patients with Hashimoto Thyroiditis. Int J Endocrinol. 2022;2022:1918674. doi:10.1155/2022/1918674
3. Ventura M, Melo M, Carrilho F. Selenium and Thyroid Disease: From Pathophysiology to Treatment. Int J Endocrinol. 2017;2017:1297658. doi:10.1155/2017/1297658
4. Southern AP, Anastasopoulou C, Jwayyed S. Iodine Toxicity. In: StatPearls. StatPearls Publishing; 2025. Accessed April 25, 2025. http://www.ncbi.nlm.nih.gov/books/NBK560770/
5. Wu K, Zhou Y, Ke S, et al. Lifestyle is associated with thyroid function in subclinical hypothyroidism: a cross-sectional study. BMC Endocr Disord. 2021;21:112. doi:10.1186/s12902-021-00772-z