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Why Your Thyroid Diagnosis Might Be a Misdiagnosis

Written by Dr. Michael Ruscio, DC on August 19, 2024

Written by Dr. Michael Ruscio, DC on August 19, 2024 — Reviewed by Hilary Watts

Thyroid Symptoms Like Brain Fog and Fatigue May Actually Be Coming From Your Gut

• Defining Hypothyroidism|
• Thyroid Conditions are Over-Diagnosed and Over-Medicated|
• Gut Health is Key to Thyroid Health|
• Thyroid Symptoms or Gut Symptoms?|
• Diet and Probiotics Are Key Strategies for Gut Healing|
• Other Supplements That Might Help|
• If You Need Medication, Take It|
• Thyroid Diagnosis & Treatment: It’s Nuanced|

Were you given an underactive thyroid diagnosis, or are you experiencing symptoms that you suspect are from low levels of thyroid hormones? If so, you’re not alone. In fact, around one in 20 Americans have some degree of hypothyroidism 1. Symptoms, when you get them, can include fatigue and brain fog, dry skin, weight gain, and feeling cold.

When hypothyroidism is a clear clinical diagnosis, treatment with thyroid hormones can be a life changer. But the reality is that there are a lot of well-meaning but off-target treatments out there for thyroid disorders. 

In fact, there’s a tendency to overdiagnose and overtreat hypothyroidism. This laser focus on “treating the numbers” can be a distraction from investigating other potential problems, like gut imbalances,  which may actually produce hypothyroid symptoms.

The good news is that hypothyroidism is frequently easier to diagnose than most think, as I’ll explain below.

Let’s dig into underactive thyroid as a diagnosis to find out what may actually be going on under the surface. Before getting started, it’s helpful to clarify some of the terminology around hypothyroidism.

Defining Hypothyroidism

You’re probably familiar with terms such as hypothyroid, sluggish thyroid, and underactive thyroid. Though these all roughly mean that your thyroid isn’t working as well as it should, it’s helpful to understand the descriptions around hypothyroidism a little better.

This way, you and your healthcare provider will be working from the same page, and you’ll also be able to understand when the terminology is a little off.

Clinical Hypothyroidism 

Clinical hypothyroidism (also known as overt hypothyroidism, frank hypothyroidism, or just hypothyroidism) is a clear-cut diagnosis when a blood test shows:

• A low level (less than 0.82 mg/dL) of the thyroid hormone free thyroxine (T4), released by the thyroid gland 2.
• AND a high level (more than 4.5 IU/mL) of thyroid stimulating hormone (TSH), released by the pituitary gland 3. 

The correct course of action for clinical hypothyroidism is to take thyroid hormone, usually as the medication levothyroxine.

Subclinical Hypothyroidism 

Subclinical hypothyroidism is when the level of thyroxine (T4) hormone is normal while TSH is high. 

However, in some situations, like being in an older age group, it’s perfectly reasonable for TSH levels to be somewhat above the standard normal range without causing any symptoms.

Thus, it may not be accurate to label everyone with marginally high TSH levels as having hypothyroidism that requires medication.

For many people, mild symptoms of subclinical hypothyroidism can be treated with appropriate diet and lifestyle improvements rather than hormone therapy.

Hashimoto’s Disease and Hashimoto’s Thyroiditis 

Hashimoto’s disease is an autoimmune disorder and the most common cause of subclinical and frank hypothyroidism in the USA. In some other parts of the world, low dietary iodine is a more common cause 1. 

The telltale sign of having Hashimoto’s disease is if your level of thyroid peroxidase (TPO) antibodies is high (above 35 IU/mL) 4. Supportive antibody testing for Hashimoto’s disease may also include TG (thyroglobulin) antibodies, but these do not accurately indicate autoimmunity 5.

Hashimoto’s disease may or may not present with hypothyroid symptoms. But it can harm the thyroid gland enough to increase TSH and reduce T4 levels,  thus progressing to Hashimoto’s thyroiditis. 

It’s important to reiterate that having Hashimoto’s disease doesn’t always lead to full-blown hypothyroidism, though it’s more likely when TPO antibodies are very high (above 500 IU/mL) 6.

In fact, the Tehran Thyroid Study, which followed the course of thyroid disease in a large cohort of people over nine years, found that those with elevated TPO antibodies had only a 9–19% chance of developing hypothyroidism after 6 years of follow-up 7 8. 

As I’ll explain below, one of the most effective ways to treat autoimmune conditions (and thereby prevent Hashimoto’s progressing into hypothyroidism) is to improve your gut health.

Sluggish Thyroid

“Sluggish thyroid” is a term some functional and integrative practitioners use to refer to lab findings that are in the “suboptimal half” of the normal range for TSH, free T4, and T3. For example, a TSH of 4.1 and free T4 of 1.0. This is very common. Sluggish thyroid is not an actual problem, and variations within these ranges are normal.

Thyroid Conditions Are Over-Diagnosed and Over-Medicated

Both conventional and natural medicine practitioners may be prone to over-diagnosing hypothyroidism. 

If it feels like your doctor has rushed to diagnose you and get you started on medication, I’d advise that you get a second opinion.

In other words, if the labs used to diagnose you did NOT show abnormally high TSH paired with abnormally low T4, then you likely do not have clinical hypothyroidism and may not need medication. 

To illustrate this, one study involved a group of 291 patients who had been taking thyroid hormone replacement therapy for years, despite not having strong diagnostic indicators of hypothyroidism. 

• During the trial, all patients stopped taking their thyroid hormone medication (levothyroxine) for 6–8 weeks while researchers monitored them 9. By the end of the trial, a surprising 61% of the patients had normal thyroid function test results and wereable to stay off their thyroid medication long-term. 

Another study validated these findings and showed that subclinical hypothyroidism will often correct itself without any intervention. The study followed 225 people diagnosed with subclinical hypothyroidism who received no treatment for 6 months. After this time, the vast majority (73.8%) had returned to normal TSH levels 10. 

This suggests that signs of hypothyroidism can come and go, and a wait-and-see approach is often best. There is no need to rush to hormone treatment unless you fall into the overt hypothyroidism category.

That said, the thyroid gland may need some attention, especially when symptoms are present. In my experience, the best way to support thyroid function and stave off hypothyroidism is to address gut health problems. 

Gut Health is Key to Thyroid Health

Some people with subclinical hypothyroidism find their TSH levels and symptoms normalize once they’ve addressed issues with their gut health. Taking care of gut infections, leaky gut, and microbiome imbalances can often prevent the need for thyroid medication or allow someone to come off medication they were already prescribed. 

Others with subclinical hypothyroidism may develop overt hypothyroidism and need to take thyroid hormone replacement therapy. However, I’ve seen many clients who followed a gut-healing program and required less thyroid medication because their healed digestive system absorbed it better. 

Why does poor gut health impact the thyroid gland so much? Well, when the gut microbiome is imbalanced, it can create inflammation and immune system disruptions that also affect thyroid function and hormone production. For example, research has shown that 11 12:

• Altered immune responses in the gut can contribute to or aggravate autoimmune conditions, including Hashimoto’s thyroiditis.
• Poor gut health can alter the activity of enzymes that impact thyroid hormone levels and reduce the absorption of minerals important to thyroid health.
• Gut inflammation can trigger brain fog, depression, and other cognitive issues that are similar to hypothyroid symptoms. 

Thyroid Symptoms or Gut Symptoms?

The final bullet point above is important because thyroid symptoms can sometimes be confused with gut symptoms. This can explain why some of my clients who have received treatment for a hypothyroid diagnosis continue to have symptoms despite returning to normal thyroid hormone levels. 

In fact, this was the case for so many of our clients that we published a case series and literature review to alert other functional and integrative practitioners to this observation.

Symptoms that can masquerade as thyroid problems but actually arise from the gut include fatigue, anxiety, brain fog, and depression 13 14 15 16

These residual problems won’t go away with continued hypothyroid treatment because the thyroid gland is not the issue. It’s the gut.

Diet and Probiotics Are Key Strategies for Gut Healing

To improve gut health in a way that supports good thyroid health, a diet that is anti-inflammatory (doesn’t cause immune reactions) and nutrient-rich is a good base.

Finding a Diet That Fits

Many of my clients do well when they follow a Paleo diet framework, which checks the above boxes without being overly restrictive.

A Paleo diet usually minimizes gluten and lactose, which research suggests may be two of the most common food sensitivities in people with hypothyroid issues.

For example, two studies showed that lactose restriction and a gluten-free diet were associated with significant decreases in TSH for Hashimoto’s patients on thyroid medication 17 18. That said, it’s important to monitor food reactions using a food and symptoms diary. Those who seem to tolerate wheat and dairy well (no gas, bloating, abdominal cramps, or other symptoms after eating them), don’t need to remove them.

Some people find their thyroid and gut symptoms worsen when they eat too many of certain carbohydrates known as FODMAPs (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols). This can feel counterintuitive if you are affected because FODMAPs are found mainly in healthy high-fiber plant foods, like garlic, onions, apples, and mangos. The reason FODMAPs are an issue for people with  particularly sensitive digestion is that gut bacteria like to ferment them, which produces a lot of gas that causes symptoms.

For clients who can’t tolerate a healthy plant-based, high-fiber diet, particularly as a result of irritable bowel syndrome (IBS), a low FODMAP diet may best suit their needs 19.

As the gut heals, it’s easier to tolerate more foods and get back to a more varied diet, which is ultimately good for gut microbiome health. You can find much more detail about elimination diets and how to do them safely for thyroid conditions if you sign up for my Thyroid Self Help Guide.

Probiotics Can Be a Game-Changer 

Probiotics can be super helpful in getting your gut back in shape. Here are some of the ways that they can promote better gut health:

• Increase the bacterial diversity, or health, of your bacterial community 20 21 22
• Fight pathogens (harmful microbes) and their toxins 20 21 23 24 25
• Promote a more rapid recovery from imbalanced gut organisms 20 21
• Promote a healthy immune response in the gut 20 21 26 27
• Reduce gut inflammation 20 21 22
• Encourage the growth of healthier microbes in the gut 20 21 26
• Reduce leaky gut, which is damage to the gut lining 20 21 28 29 30

Remember, probiotics create a healthy gut, which means a healthier thyroid gland. One study found that when hypothyroid patients improved their gut health with probiotics, they were able to use less of the thyroid medication levothyroxine (Synthroid) 31. 

If you’re a little confused about which probiotics to take, it helps to know that nearly every probiotic product can be classified into one of these three categories 32:

• Lactobacillus and Bifidobacterium blend
• Saccharomyces boulardii (a healthy fungus)
• Soil-based bacillus species

Some of my clients do better by taking just one product from one category—usually a Lactobacillus and Bifidobacterium blend. However, studies suggest that mixtures of probiotics taken together tend to be more effective 33 34. Generally, my clients also report that a triple therapy approach, which means taking one probiotic from each of the above three categories, often achieves better results. 

Regardless, it’s ideal to give probiotics a trial period of 2–3 months to make sure to give the body a chance to reap the full benefits. 

Other Supplements That Might Help

Probiotics are the only supplement that I would routinely recommend for everyone with thyroid disease. But I want to draw your attention to some other supplements that might be of use, depending on your individual circumstances. The following table details each supplement and  how it might help with thyroid health.

What About Iodine?

Though iodine deficiency is a key cause of hypothyroidism (goiter) in some parts of the world, too much can also be a problem. Iodine supplementation is not recommended in the USA, where iodine intakes are generally sufficient. That’s because too much iodine can actually increase the incidence of thyroid autoimmunity 54 and is a risk factor for hypothyroidism 55.

This means you should only take supplemental iodine if you know you’re absolutely deficient.

If You Need Medication, Take It

Though I’ve made the case that many patients are given thyroid hormone replacement therapy too readily, medication can still be important for some. If your T4 and TSH tests indicate to your doctor that thyroid medication is necessary (see above in the Defining Hypothyroid section), you should definitely go ahead with it.

The conventional medicine choice is usually to give thyroxine (T4) hormone in its synthetic form (levothyroxine).

However, there is another thyroid hormone medication sometimes used in combination with T4. It is triiodothyronine (or T3), the more active thyroid hormone the body makes from T4.

Many functional health practitioners prefer using a combination of T4 and T3 (made from dried pig thyroid), based on the assumption that the body might have a hard time converting T4 to T3. 

However, the evidence for combining T3 and T4 isn’t impressive. One meta-analysis (the highest-quality type of research) and a review of literature have shown that there is no reliable evidence that combining T4 with T3 is better than T4 alone for treating symptoms 56 57. 

That said, a review paper found that patients preferred T3-T4 combination therapy over T4 alone 50–70% of the time 57.

Nonetheless, synthetic T4 works and is a more consistent and regulated product without significant side effects. Like the American Thyroid Association, I do not recommend combining T4 and T3 58.

If T4 alone doesn’t resolve my clients’ symptoms, or if they feel unhappy with their results, then I’ll recommend they ask their thyroid doctor to try a combination of T3 and T4.

Thyroid Diagnosis & Treatment: It’s Nuanced

If you’ve been uncertain or confused about your hypothyroid symptoms or thyroid hormone levels, I hope you now can now make sense of the complexity of this topic. 

The bottom line is that hypothyroidism exists on a spectrum. Depending where you are on that spectrum, you may or may not need hormone therapy.

Whether you require medication or not, it pays to care for your gut health, which can help reduce symptoms such as brain fog and fatigue that are typical of both gut problems and hypothyroidism.

If you’d like to work through your thyroid issues in more depth, please check out my thyroid course, which will show you how to manage thyroid conditions. Or, if you prefer, reach out for a virtual one-to-one consultation with one of our highly experienced practitioners.

The Ruscio Institute has also developed a range of high-quality formulations to help our patients and audience. If you’re interested in learning more about these products, please click here. Note that there are many other options available, and we encourage you to research which products may be right for you.