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Thyroid 101: The Key Differences Between Hypothyroidism, Hyperthyroidism, Hashimoto’s, and Graves’ Disease

Your thyroid is a small, butterfly-shaped gland - but don’t let its size fool you. It plays a vital role in regulating your metabolism, energy, temperature, digestion, mood, and even your menstrual cycle. When it’s out of balance, you feel it everywhere.


And yet, thyroid issues are notoriously underdiagnosed, misdiagnosed, or misunderstood. Many women are told their symptoms are “in their head” or are brushed off with incomplete lab work and vague advice.


At Solara Functional Wellness, we believe clarity leads to healing. That starts with understanding the different types of thyroid dysfunction - so you can be informed, empowered, and get the care you truly need.



Quick Overview of the Thyroid Gland


The thyroid gland is a small, butterfly-shaped organ located at the front of the neck, just below the larynx (voice box). Despite its size, it has a profound influence on nearly every metabolic process in the body.


The thyroid is part of the endocrine system and primarily functions to produce, store, and release hormones that regulate the body’s metabolism, energy production, temperature regulation, cardiovascular function, gastrointestinal motility, and even reproductive health.


The primary hormones it produces include:

  • Thyroxine (T4): The main hormone produced by the thyroid. It acts largely as a storage form of thyroid hormone and must be converted into T3 to be biologically active.

  • Triiodothyronine (T3): The active form of thyroid hormone that directly influences cellular metabolism. Most T3 is produced by the peripheral conversion of T4 in the liver, gut, and other tissues.

  • Reverse T3 (rT3): An inactive form of T3 that can block thyroid receptors when elevated—often a response to stress, inflammation, or illness.

  • Thyroid-Stimulating Hormone (TSH): Produced by the pituitary gland in the brain, TSH signals the thyroid to produce more T4 and T3 as needed. It’s often used as a conventional screening marker but doesn’t tell the full story on its own.


Key Insight:


Proper thyroid function is not only about how much hormone is produced, but also how efficiently the body converts, transports, and utilizes those hormones at the cellular level. That’s why functional medicine looks beyond just TSH - assessing patterns of imbalance, nutrient co-factors, and potential autoimmune triggers that may interfere with optimal thyroid signaling.


Hypothyroidism


Hypothyroidism occurs when the thyroid is underactive and doesn’t produce enough thyroid hormones.


Common symptoms of Hypothyroidism include:

  • Fatigue and brain fog

  • Weight gain or inability to lose weight

  • Constipation

  • Dry skin and hair thinning

  • Depression or mood swings

  • Cold intolerance

  • Menstrual irregularities


Common causes: of Hypothyroidism:

  • Iodine deficiency (less common in the U.S.)

  • Hashimoto’s thyroiditis (an autoimmune condition)

  • Certain medications, nutrient deficiencies, or stress-related dysfunction


Without enough thyroid hormone, your body slows down - physically and mentally.


Hyperthyroidism


Hyperthyroidism occurs when the thyroid is overactive and produces too much hormone, speeding everything up in the body.


Common symptoms of Hyperthyroidism include:

  • Anxiety or irritability

  • Rapid heartbeat or palpitations

  • Weight loss despite normal or increased appetite

  • Insomnia

  • Heat intolerance

  • Tremors

  • Increased bowel movements


Common causes of Hyperthyroidism:

  • Graves’ disease (autoimmune)

  • Thyroid nodules that produce excess hormone

  • Thyroiditis (inflammation)


If left unaddressed, hyperthyroidism can lead to heart complications and bone loss.


Hashimoto’s Thyroiditis


Hashimoto’s is the most common cause of hypothyroidism in the U.S. It’s an autoimmune condition where the immune system attacks the thyroid tissue, causing chronic inflammation and gradual decline in hormone production.


What sets it apart:

  • It’s not just low thyroid function - it’s a chronic immune issue.

  • Many people with Hashimoto’s experience symptoms long before their TSH becomes abnormal.

  • Fluctuating symptoms are common, especially in early stages.


Why antibody testing matters:

Most conventional labs only test TSH and maybe T4. But with Hashimoto’s, you need to test thyroid peroxidase (TPOAb) and thyroglobulin antibodies (TGAb) to get a complete picture.


Graves’ Disease


Graves’ disease is the leading autoimmune cause of hyperthyroidism. In this condition, the immune system produces TSH receptor antibodies (TRAb) that overstimulate the thyroid, causing it to overproduce hormones.


What sets it apart:

  • It’s immune-driven - like Hashimoto’s, but in the opposite direction.

  • You may experience bulging eyes (Graves’ ophthalmopathy), anxiety, and heart palpitations.

  • Antibody testing and imaging may be used to confirm diagnosis.


Just like Hashimoto’s, Graves’ often has immune system imbalances and gut involvement at its core.


Functional Medicine Perspective


In conventional medicine, thyroid care often revolves around monitoring TSH and adjusting medication dosage accordingly. While this may work for some individuals, it frequently overlooks the broader picture - especially in cases of unresolved symptoms despite “normal” labs.


At Solara Functional Wellness, we take a root-cause, systems-based approach to thyroid health that goes far beyond TSH alone. Our goal is not only to normalize lab values but to optimize your thyroid function and overall well-being.


Here’s how our approach to Thyroid Disorders differs:

  • Comprehensive lab evaluation: We assess a full thyroid panel, including TSH, free T3, free T4, reverse T3, and thyroid antibodies (TPOAb, TGAb, TRAb when indicated) to provide a more complete and accurate picture of thyroid function.

  • Functional reference ranges: Instead of relying solely on conventional lab cutoffs, we interpret results using functional ranges—those associated with optimal physiological function rather than simply the absence of disease.

  • Identifying upstream drivers: We explore contributing factors such as gut dysbiosis, chronic inflammation, nutrient deficiencies (e.g., selenium, iodine, zinc, iron, B12), toxic burden, and HPA axis dysregulation that may be impairing thyroid function.

  • Immune system support: In autoimmune thyroid conditions like Hashimoto’s and Graves’ disease, we focus not only on hormone regulation but also on calming immune reactivity and restoring immune tolerance.

  • Whole-person care: Recognizing the intricate relationship between the thyroid, gut, brain, adrenal glands, and reproductive hormones, we create personalized protocols that address nutrition, lifestyle, stress, and environmental exposures.


Ultimately, functional medicine views thyroid dysfunction not as an isolated glandular issue, but as part of a complex, interdependent system. Our job is to uncover where that system is breaking down and support your body in healing from the inside out.


Conclusion


Your thyroid health is too important to overlook. Whether you’re dealing with fatigue, mood swings, or unexplained weight changes, the first step is getting the right diagnosis - and that means looking at the full picture.


At Solara Functional Wellness, we specialize in identifying and addressing the root causes of thyroid dysfunction using a personalized, whole-body approach.


References:

Caturegli, P., De Remigis, A., & Rose, N. R. (2014). Hashimoto thyroiditis: Clinical and diagnostic criteria. Autoimmunity Reviews, 13(4–5), 391–397. https://doi.org/10.1016/j.autrev.2014.01.007


Chaker, L., Bianco, A. C., Jonklaas, J., & Peeters, R. P. (2017). Hypothyroidism. The Lancet, 390(10101), 1550–1562. https://doi.org/10.1016/S0140-6736(17)30703-1

De Leo, S., Lee, S. Y., & Braverman, L. E. (2016). Hyperthyroidism. The Lancet, 388(10047), 906–918. https://doi.org/10.1016/S0140-6736(16)00278-6


Kim, H. Y. (2023). Overview of thyroid diseases: Understanding the basics. Yeungnam University Journal of Medicine, 40(2), 87–96. https://doi.org/10.12701/yujm.2023.00420

Jiang, W., Lu, G., Gao, D., Lv, Z., & Li, D. (2022). The relationships between the gut microbiota and its metabolites with thyroid diseases. Frontiers in endocrinology, 13, 943408. https://doi.org/10.3389/fendo.2022.943408


Cyna, W., Wojciechowska, A., Szybiak-Skora, W., & Lacka, K. (2024). The Impact of Environmental Factors on the Development of Autoimmune Thyroiditis-Review. Biomedicines, 12(8), 1788. https://doi.org/10.3390/biomedicines12081788

Singh, A., Berberich, A. J., & Singh, R. J. (2024). Graves’ disease: Current diagnosis and management. Advances in Clinical Chemistry, 119, 193–212. https://doi.org/10.1016/j.acc.2024.03.005


Tomov, D. G., Levterova, B. A., Mihailova, V. N., Troev, D. M., Miteva, M. Z., Uzunova, Y. I., & Orbetzova, M. M. (2024). Influence of the increase in intestinal permeability and microbiota change in the development of Hashimoto's thyroiditis: Systematic review. Endocrine Metabolic Science, 14, 100195. https://doi.org/10.1016/j.endmts.2024.100195

 
 
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