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Hyperthyroidism vs. Hypothyroidism

Written by Dr. Ruscio on June 3, 2022

Written by Dr. Ruscio on June 3, 2022 — Reviewed by Hilary Watts

Dr. Michael Ruscio is a DC, Naturopathic Practitioner, researcher, and clinician. He serves as an Adjunct Professor at the University of Bridgeport and has published numerous papers in scientific journals as well as the book Healthy Gut, Healthy You. He also founded the Ruscio Institute of Functional Health, where he helps patients with a wide range of GI conditions and serves as the Head of Research.

The Difference and Why Targeting Your Gut Health Can Improve Symptoms of Both

• Thyroid Basics|
• Hypothyroidism|
• Hyperthyroidism|
• Hyperthyroidism vs. Hypothyroidism|
• The Gut-Thyroid Connection|
• Natural Therapies|
• The Bottom Line|

Your thyroid gland is an endocrine organ that’s responsible for many of your body functions like metabolism, sleep, digestion, and hormone balance. When your thyroid isn’t functioning properly, you can experience everything from mood and weight changes to vocal hoarseness and digestive distress. If you’ve been feeling more tired lately or seem to have trouble maintaining your weight, it’s easy to think you may have a thyroid problem. 

While both hypothyroidism (low thyroid hormone) and hyperthyroidism (elevated thyroid hormone) can share symptoms like digestive distress and fatigue, their other classic symptoms are quite different. However, many symptoms of thyroid dysfunction are non-specific and often overlap those of other disorders, especially digestive disorders. 

Before worrying unnecessarily and jumping to conclusions, it’s important to remember that blood work (and the correct interpretation of that blood work) is required to diagnose a true thyroid disorder and to further distinguish between hyperthyroidism vs. hypothyroidism. 

In this article, we’ll break down hyperthyroidism vs. hypothyroidism, including the causes, symptoms, and prevalence of each. We’ll also discuss how your gut health factors in and how natural therapies can be an important part of treatment for those with true thyroid disorders and those with thyroid disorder symptoms despite normal blood levels.

Thyroid Basics

Before we dive into the specifics of hyperthyroidism vs. hypothyroidism, let’s quickly review what the thyroid is and its functions in the body.

The thyroid is a hormone-producing gland that’s found at the front of the neck, just beneath your voice box [1]. Normally, the thyroid gland creates thyroid hormones after the hypothalamus in the brain secretes thyrotropin-releasing hormone (TRH), which cues the pituitary gland to release thyroid-stimulating hormone (TSH) [2].

TSH tells the thyroid gland to produce thyroxine (T4) — making up 80% of total thyroid hormone — and L-triiodothyronine (T3) — 20% of thyroid hormone. T4 and T3 then bind to thyroid receptor cells all throughout your body to regulate a variety of functions like [1, 2]:

• Energy production
• Digestive function
• Heart and muscle function
• Body weight
• Body temperature
• Fertility
• Brain and nervous system function

Since the thyroid gland is involved in so many important processes, any breakdown in the system can create a whole host of negative symptoms with potential health consequences. 

What Is Hypothyroidism?

Hypothyroidism (underactive thyroid) occurs when the circulating thyroid hormone levels in the body are too low [3]. Hypothyroidism is diagnosed when blood TSH levels are high and free T4 levels are low.

There are three different categories of hypothyroidism [2]:

1. Primary hypothyroidism (represents 99% of hypothyroid patients) occurs when the thyroid gland can’t produce enough thyroid hormone. This can result either from autoimmunity or if the thyroid has been surgically removed (thyroidectomy) due to thyroid cancer or severe hyperthyroidism.
2. Secondary hypothyroidism (rare) occurs when the thyroid gland is normal, but the pituitary gland is not producing TSH.
3. Tertiary hypothyroidism (rare) occurs when the hypothalamus doesn’t produce enough TRH.

Subclinical hypothyroidism (elevated TSH with normal free T4) may also be diagnosed but usually doesn’t require treatment because thyroid function often normalizes on its own [4, 5].

While the most common cause of hypothyroidism worldwide is iodine deficiency, in the United States, it’s Hashimoto’s thyroiditis, an autoimmune condition where the immune system creates antibodies that attack thyroid gland tissue [3].

What Are the Symptoms of Hypothyroidism?

People with hypothyroidism can experience a variety of symptoms, but there are some main symptoms that seem to be most suggestive of hypothyroidism [3, 6, 7, 8, 9, 10]:

• Fatigue
• Dry skin
• Mood swings
• Cold intolerance
• Hair loss
• Trouble swallowing
• Weight gain

Other symptoms may include:

• Constipation
• Muscle pain
• Hoarseness
• Shortness of breath
• Frontal neck pain
• Heart palpitations
• Vertigo
• Wheezing
• Irregular menstrual cycles
• Muscle cramps

Symptoms alone aren’t a reliable indicator of hypothyroidism, so if you’ve got one or two of these, it’s probably not cause for concern. If you have four or more of the main symptoms though, you may want to have your healthcare provider order some specific blood tests (TSH, free T4, and thyroid antibodies) to dig a little deeper.

How Common Is Hypothyroidism?

Subclinical hypothyroidism affects 4.6% of those over the age of 12, with true hypothyroidism affecting 0.3%. It’s important to note that hypothyroidism symptoms often mimic those of digestive disorders, which occur far more often [3, 11, 12].

In the clinic, we’ve noticed a trend toward the over-diagnosis and treatment of subclinical hypothyroidism by well-meaning functional medicine practitioners and other providers who may be a little too aggressive in their interpretation of thyroid lab values. Observational research shows that 35-60% of people taking hypothyroid medication don’t actually need it, and their labs normalized after discontinuing medication [5, 13]. The issue here is when you use thyroid medication for someone who doesn’t have true hypothyroidism, it can actually lead to side effects like:

• Weight gain
• Hair loss
• Fatigue
• Poor mood
• Sleep disturbances

In addition to troubling side effects, labeling and treating someone with hypothyroidism when they don’t actually have the condition adds unnecessary stress and burdens them with a lifetime of medication that’s inconvenient and costly. That’s why it’s so important to work with a provider who is familiar with the diagnosis and treatment of overt versus subclinical hypothyroidism.

What Is Hyperthyroidism?

Hyperthyroidism (overactive thyroid) occurs when the thyroid produces too much thyroid hormone [14]. To diagnose hyperthyroidism, blood TSH levels should be low and free T4 should be high. 

Like hypothyroidism in the U.S., the most common cause of hyperthyroidism is an autoimmune disorder that attacks the thyroid gland called Graves’ disease (responsible for 60-80% of hyperthyroid cases) [15]. 

Other causes include:

• Thyroid nodules (toxic multinodular goiter): Thyroid nodules make thyroid hormone despite brain signals telling the thyroid to stop thyroid hormone production [14].
• Thyroiditis (inflammation of the thyroid gland): Can be caused by viral infections [16], radiation [17], certain medications [18], or recent childbirth [19].

If left untreated, excessive thyroid hormone traveling around the body can lead to heart damage and a life-threatening “thyroid storm” (rare) [20].

What Are the Symptoms of Hyperthyroidism?

While they share some common symptoms, like digestive upset, sleep disturbances, and fatigue, the majority of hyperthyroidism symptoms are quite the opposite of hypothyroidism. 

The most common symptoms include [14]:

• Weight loss despite a higher appetite
• Heart palpitations
• Nervousness 
• Tremors 
• Difficulty breathing 
• Fatigue 
• Diarrhea or frequent bowel movements 
• Muscle weakness 
• Heat intolerance 
• Sweating more than usual 
• Irregular menstrual cycles 

Additional possible symptoms include [21]:

• Anxiety
• Irritability
• Difficulty sleeping
• Irregular heartbeat
• Goiter
• Erectile dysfunction or loss of libido
• Thyroid eye disease (eye bulging, tearing, dryness, irritation, puffy eyelids, inflammation, light sensitivity, blurred vision, pain) [14]
• Thick, red skin on the shins or tops of the feet

How Common Is Hyperthyroidism?

Hyperthyroidism is relatively uncommon and affects roughly 1.2% of people in the U.S. [22]. Graves’ disease specifically affects about one in 200, the majority of whom are women [22, 23, 24]. Furthermore, there doesn’t appear to be an issue with the overdiagnosis of hyperthyroidism as there is with hypothyroid disorders. 

Hyperthyroidism vs. Hypothyroidism

Now that we’ve discussed the specifics of each disorder, let’s take a look at a side-by-side comparison of hyperthyroidism vs. hypothyroidism:

The Gut-Thyroid Connection

Digestive symptoms are common in both gut and thyroid conditions, and research suggests that your gut health strongly influences your thyroid function and your risk for autoimmunity [25]. Increased intestinal permeability (leaky gut) is one contributor to the development of autoimmune diseases like Graves’ disease and Hashimoto’s thyroiditis. It can be caused by imbalances in the gut microbiome and by eating gluten (a protein found in some grains) [26, 27, 28, 29, 30, 31, 32, 33, 34, 35].

Gut issues can mimic hypothyroidism by causing similar symptoms like [36, 37]:

• Fatigue
• Brain fog
• Depression
• Mood changes
• Cold intolerance
• Anxiety

In addition, H. pylori infection and small intestinal bacterial overgrowth (SIBO) are two gut conditions strongly associated with hypothyroidism [38].

Successful treatment of these underlying gut issues (gut infections, intestinal permeability, microbiome imbalances) with diet, lifestyle, and probiotics can significantly improve these symptoms and even thyroid lab markers [39, 40, 41, 42]. Three studies found patients treated for H. pylori experienced improved TSH levels, with some patients requiring less thyroid medication after treatment [43, 44, 45]. 

In my experience, a small percentage of “thyroid patients” will discover that their TSH levels completely normalize once their gut issues have been treated and they can discontinue thyroid medication. Other patients may need to continue taking thyroid hormone replacement (like levothyroxine) but, after healing the gut and reducing symptoms, can more easily optimize their medication strength.

In the clinic, we often see patients being treated for a thyroid condition when it’s really poor gut health at the heart of their symptoms. If you’re being treated for the symptoms of hypothyroidism or hyperthyroidism that just don’t seem to resolve despite being on thyroid medication, you may actually be experiencing the symptoms of an unhealthy gut.

Natural Therapies for Thyroid Health

If you’re experiencing the symptoms of a thyroid disorder, it’s important to get some routine blood work (including TSH, free T4, and thyroid antibodies). If you’ve already been diagnosed with hyperthyroidism or hypothyroidism, it’s important to remember that natural therapies targeting gut health can sometimes improve thyroid health and symptoms dramatically [43, 44, 45, 46, 47, 48, 49]. 

I recommend starting with diet, lifestyle, and probiotics:

• The Paleo diet is a whole-foods, anti-inflammatory meal plan that reduces exposure to foods that may trigger an immune response (like gluten) and reduces inflammation [50, 51].
•  Lifestyle changes like exercise, stress management, daily sun exposure, and restful sleep are also effective for gut healing and improving thyroid disease symptoms [52, 53, 54].
• Probiotics can help rebalance the gut microbiome and the immune system, reduce gut inflammation, repair the gut lining, and may improve thyroid symptoms [55]. They’re extremely safe and effective, so definitely worth adding to your daily protocol.

If your levels are in the normal ranges or if you’ve been diagnosed with subclinical hypothyroidism, then focus on improving your gut health with nutrition and lifestyle strategies, which often bring much symptom relief. My book, Healthy Gut, Healthy You includes a do-it-yourself guide and is a great place to start.

Gut Healing Strategies = Thyroid Symptom Relief

Hyperthyroidism and hypothyroidism share some common symptoms like digestive distress and fatigue, but other symptoms are very different. Neither disorder can be diagnosed without standard blood testing. 

If you’re experiencing a fair number of thyroid disease symptoms, speak with your healthcare provider about checking TSH and free T4 levels. If your thyroid labs are within normal range, implement the above gut-healing strategies and monitor how your symptoms improve. If your provider recommends thyroid medication for lab values that are in the normal ranges, it may be time to seek out a second opinion from a functional medicine or thyroid-savvy practitioner. 

If your TSH and free T4 levels are flagged high or low based on standard lab ranges, try implementing our gut-healing strategies while working with your healthcare provider to determine the best conventional treatment.

If you’ve gotten your diet and lifestyle in order but still struggle with uncomfortable health symptoms, come see us in the clinic for a more personalized plan.

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