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Worried About Your Thyroid Health? Ask Your Doctor For These 3 Thyroid Labs

Medically reviewed by 
Worried About Your Thyroid Health? Ask Your Doctor For These 3 Thyroid Labs

There's a growing awareness of the importance of thyroid health and how to detect early symptoms of thyroid dysfunction. It's estimated that upwards of 20 million Americans have some form of thyroid dysfunction and that up to 60% of those affected are unaware of their condition.

This is why it's vital that everyone is well versed in the thyroid, its functions, and how to detect early symptoms of thyroid dysfunction.


What is The Thyroid?

The thyroid is a butterfly-shaped gland located at the base of the neck, and it is centrally important to metabolic and hormonal health. It is part of the endocrine system, which is the system in the body involved in making and releasing various hormones.

While the conventional healthcare model primarily uses TSH alone as a screening marker for thyroid disease, functional medicine models often promote the importance of understanding the entire thyroid hormone cascade to evaluate thyroid health. This involves testing TSH, T3, T4, and sometimes TPO (if needed).

Why is the Thyroid So Important?

The thyroid gland makes two primary hormones, triiodothyronine (T3) and thyroxine (T4). Two glands in the brain - the pituitary and hypothalamus - work together to help maintain ideal thyroid hormone levels, primarily through the pituitary-mediated release of thyroid-stimulating hormone (TSH).

TSH communicates with the thyroid gland to make more or less thyroid hormone, depending on levels of these hormones in the body. TSH is the most common lab test ordered for the thyroid and can give insight into whether the body thinks it has adequate, not enough, or too little thyroid hormone.

How well your thyroid functions impacts many different vital parts of your physiology, including:

  • Metabolism and body weight
  • Heart rate
  • Digestion
  • Nervous System
  • Immune System
  • Breathing
  • Menstrual Cycles
  • Cholesterol levels
  • Body temperature
  • Muscle strength and the ability to gain muscle mass

How Thyroid Hormones Communicate With Each Other

  • The thyroid gland makes two primary hormones, T4 and T3.
  • T4 is the predominant hormone, with 90% of thyroid hormone produced as T4.
  • T4 is converted to T3, the active form of thyroid hormone, by tissue-specific enzymes called deiodinases.
  • How does the thyroid know when to make more thyroid hormone? When the hypothalamus senses insufficient thyroid hormone in the circulation, it responds by secreting a hormone called TRH (thyroid-releasing hormone).
  • TRH, in turn, signals the pituitary gland to synthesize more TSH (thyroid-stimulating hormone).
  • TSH then signals the thyroid to increase T4 and T3 production, ultimately raising levels in circulation.

What is Thyroid Disease?

Thyroid disease is a general term for any condition that prevents your thyroid from making - or regulating - the optimal amount of thyroid hormone.  

If the body makes too much thyroid hormone, your body can expend energy too quickly. This state of excess thyroid hormone is called hyperthyroidism. When your body expends energy too quickly, it can make you nervous or anxious, cause unwanted weight loss, and make retaining muscle difficult.  

The opposite disorder in which the body makes too few thyroid hormones is hypothyroidism. When your body doesn't have enough thyroid hormone, you may feel tired, have trouble concentrating, or may gain weight despite diet and exercise.  

Several different conditions can cause hypothyroidism or hyperthyroidism. Women are more likely to experience thyroid disease than men, with 1 in 8 women developing a thyroid disorder during their lifetime.  

Causes of Hypothyroidism

Autoimmune disease

Hashimoto's disease is an autoimmune condition that is the leading cause of hypothyroidism. In this disease, the immune system attacks the thyroid, causing inflammation resulting in an inability to make adequate thyroid hormone. While genetics may play a role in developing autoimmune conditions such as Hashimoto's, the environment is also a piece of the puzzle, with studies linking toxin exposure, poor nutrition, and high-stress levels to a higher risk of autoimmunity.

Iodine deficiency

While uncommon in the U.S., iodine deficiency is a leading cause of hypothyroidism worldwide. This cause of hypothyroidism is characterized by a goiter due to enlargement of the thyroid gland.

Postpartum Thyroiditis

Inflammation of the thyroid can affect 5-10% of women in the first year after giving birth. The condition is typically temporary, but it's essential to screen thyroid function in women during and after pregnancy.


Inflammation of the thyroid is called thyroiditis. When the thyroid becomes inflamed, stored thyroid hormone can leak out, causing an initial surge of thyroid hormone, followed by an extended period of underactive thyroid activity. An inflamed thyroid may occur after an infection, in response to medication, in cases of gut dysbiosis, or following radiation.

Chronic Dieting (particularly when paired with excessive exercise)

Extended periods of low-calorie diets are associated with increased stress hormones and decreased thyroid hormone, resulting in less-than-optimal thyroid function and its symptoms. While exercise is essential to a healthy lifestyle, the "dose" matters, and it's vital to fuel the body appropriately.

Surgical Removal of Thyroid Gland

Surgical removal of the thyroid gland may be recommended in some instances, such as a thyroid cancer diagnosis or ongoing hyperthyroidism.

A complete thyroidectomy removes the entire thyroid gland. The patient is, by definition, hypothyroid as a baseline, with medication being used to replace the hormones that are no longer being produced. However, since most prescriptions are still only T4 medications, it's possible to see hypothyroidism in this population because of incorrect dosage, potential absorption, or T4 to T3 conversion issues.

In a hemi-thyroidectomy, only the affected part of the thyroid is removed, leaving some of the gland intact. While some patients can regain normal thyroid function after partial removal of the gland, the rates of hypothyroid incidence range from 5-41.9% in various studies, so it's still important to monitor thyroid hormones in this population.

Drug-Induced Hypothyroidism

Drug-induced hypothyroidism is when a medication you're taking causes your thyroid gland to be less active or causes your thyroid gland to shrink so that it produces less thyroid hormone. It's imperative to find a balance where your levels aren't too high or too low and discuss with your doctor if you start noticing hypothyroid symptoms after starting a new medication.

Other Causes of Hypothyroidism

Less commonly, conditions such as congenital hypothyroidism, surgical damage to the thyroid or pituitary gland, and radiation treatment to the throat can also result in hypothyroidism.

Hypothyroid Signs & Symptoms

Hypothyroidism happens when there is too little T3 and T4 in the body and can cause symptoms such as:

  • Trouble sleeping
  • Weight gain, regardless of nutrition and exercise
  • Depression
  • Dry skin
  • Brittle hair or hair thinning
  • Loss of the outer third of the eyebrow
  • Brain fog and difficulty concentrating
  • Fatigue
  • Cold body temperature and sensitivity to cold
  • Joint and muscle pain, muscle cramps
  • Heavy periods
  • Constipation and bloating
  • High cholesterol

Causes of Hyperthyroidism

Autoimmune Disease

Graves' disease is an autoimmune disease that produces too much thyroid hormone. It's more common among women and people under 40 years of age.  

Post-Partum Thyroiditis

Postpartum thyroiditis can result in hyperthyroidism after birth and ultimately leads to hypothyroidism. This is usually temporary, but if you are experiencing anxiety, extreme weight loss, and restlessness after birth, it's essential to bring these symptoms up with your doctor.


Just as thyroiditis can cause hypothyroidism, it can also result in hyperthyroidism. When the thyroid becomes inflamed, the stored hormone can leak out, causing a surge of thyroid hormone in the circulating and a hyperthyroid state in the body. Left unchecked, a condition called thyrotoxicosis may develop, in which dangerously high thyroid hormone levels are circulating.  

Excessive Iodine

Certain cough syrups, medications (including some heart medications), and seaweed-based supplements may all contribute to excessive levels of iodine in the body, causing hyperthyroidism to develop.  

Factitious Hyperthyroidism

Sometimes, an incorrect thyroid medication dose can cause thyroid hormone levels to become too high, resulting in hyperthyroidism. This can also occur with taking glandular supplements that aren't regulated. In both cases, it's important to work with a practitioner to monitor your thyroid levels to make sure you're taking the appropriate dosage for your case.

Other Causes of Hyperthyroidism

In some rare cases, a benign pituitary tumor can cause hyperthyroidism.

Hyperthyroid Signs & Symptoms

Hyperthyroidism occurs when there is too much T3 and T4 in the body and can result in symptoms such as:

  • Anxiety, irritability, or mood swings
  • Rapid heart rate (tachycardia) and/or heart palpitations
  • Weight loss (unintentional)
  • Hyperactivity
  • Hair loss
  • Missed or very light menstrual periods
  • Trembling hands
  • Increased sweating and body temperature
  • Diarrhea
  • Nervousness
  • Muscle spasm or muscle weakness
  • Trouble sleeping

How is Thyroid Disease Diagnosed

A functional medicine practitioner will often test a more extensive thyroid panel to evaluate thyroid function, including TSH, total T4 and T3, free T4 and T3, reverse T3, and thyroid antibodies. Additionally, functional medicine practitioners often look at optimal ranges for lab markers.

Most standard, conventional lab ranges for TSH indicate that a TSH between 0.4-4.5 mIU/L is normal, while the functional medicine reference range for TSH is 0.5-2.5 mIU/L.  

According to the conventional medicine reference range, those with TSH values in the higher "normal" range (2.5-4.5 mIU/L) may be what's referred to as a "subclinical hypothyroid" population. Yet, these individuals are told their lab values are normal, missing a critical window to correct thyroid hormones before it leads to thyroid disease.

The table below lists the standard versus functional medicine reference ranges for thyroid lab values.

Conventional vs. Functional Medicine Optimal Thyroid Lab Ranges:

A detailed personal history helps a functional medicine practitioner determine what lab tests will be most helpful for each individual case of thyroid disease. Other labs may be ordered to help see the "bigger picture" of what could be contributing to thyroid disease, including:

Physical Exam

A functional medicine practitioner may also recommend a thyroid ultrasound to rule out tumors and evaluate the presence of nodules on the thyroid. Most thyroid nodules are benign, and an ultrasound-guided biopsy can determine if this is the case. Most nodules don't cause signs or symptoms, but larger nodules may cause difficulty swallowing, voice changes, or shortness of breath. In some cases, a thyroid nodule may produce additional thyroid hormone on its own, leading to symptoms of thyroid disease.  

Conventional Treatment for Thyroid Disease

Conventional treatment for thyroid disease typically involves medication based on TSH values. Surgery may also be an option depending on the diagnosis.

Conventional Treatment for Hypothyroidism

Typically, a T4 medication such as levothyroxine is prescribed for hypothyroidism, with continual monitoring of TSH levels and adjusting dosage as needed.

Conventional Treatment for Hyperthyroidism

An antithyroid agent (methimazole or propylthiouracil) and possibly a beta-blocker to help regulate symptoms are typically prescribed for hyperthyroidism.

Radioactive iodine may be used to intentionally damage the thyroid, preventing it from producing excess thyroid hormone. In some cases, surgically removing the thyroid and prescribing a T4 medication to replace the thyroid hormone are recommended.

6 Natural Ways Functional Medicine Doctors Treat Thyroid Dysfunction

Functional Medicine treatment for thyroid disease may include nutritional recommendations, targeted herbs, supplements, and lifestyle changes to address the root cause of thyroid dysfunction. Depending on each case's severity, these interventions may be used alongside prescription or alone.

1: Nutrition

In cases of autoimmune thyroid disease, a functional medicine practitioner may recommend an anti-inflammatory diet that eliminates any foods causing an immune response and leading to more inflammation in the body. Such a nutritional approach may decrease systemic inflammation and help modulate the immune system, which can help manage autoimmune thyroid conditions.

Healthy fats, such as omega-3s, have been linked to enhanced thyroid hormone function, making them an essential component of a thyroid-supporting diet.  

There's been some evidence that a gluten-free diet may benefit those dealing with Hashimoto's disease, as these individuals may have higher rates of celiac disease or non-celiac gluten sensitivity. Several studies show a strong link between Hashimoto's and Graves' and gluten intolerance. The link is so well-established that researchers suggest all people with autoimmune thyroid disease be screened for gluten intolerance and vice versa.

What's the Connection between Gluten and The Thyroid?

The molecular structure of the protein in gluten (gliadin) closely resembles that of the thyroid gland. When gliadin is ingested, the immune system can not distinguish between this protein and the thyroid gland. This causes a cascading effect of antibodies attacking both the gluten and the thyroid tissue.

In some individuals with poor thyroid function, excessive raw goitrogenic foods - including cauliflower, kale, cabbage, turnip, radish, and cassava - may decrease thyroid function. Cooking these foods reduces the potential for a negative impact on the thyroid, which allows individuals to keep a varied diet without experiencing unwanted symptoms.  

For those on thyroid medication, certain foods may impact the absorption of the medication, including grapefruit, soy, and raw cruciferous vegetables (like broccoli and cabbage), so it's important to watch the timing of these foods around taking medication.

A nutrient-dense diet that supplies all of the essential vitamins and minerals needed for thyroid hormone production, as well as adequate protein and a balanced ratio of healthy fats and carbohydrates, is an important component of managing any thyroid condition. Foods rich in minerals such as Brazil nuts (selenium), poultry and lean red meat (zinc), shellfish (zinc and copper), organ meats (zinc, copper, and iron), pumpkin seeds (zinc), seaweed (iodine) all support healthy thyroid function, while B-vitamin rich foods such as eggs, vegetables, salmon, and chickpeas are also good choices. A functional medicine practitioner will help guide you towards the best food sources of thyroid nutrients for your particular body.

Depending on the root cause of a given case, a functional medicine practitioner may guide a thyroid patient through different therapeutic diets to help reduce inflammation, address gut dysbiosis, or support metabolic health while leading the patient toward a sustainable, balanced anti-inflammatory lifestyle.  

2: Herbs and Supplements

An herb and supplement protocol for thyroid health depends on the root causes of given thyroid disease.

  • Minerals such as selenium, iodine, zinc, and iron are essential for thyroid health. While these can be consumed in the diet directly, those dealing with gut issues or autoimmune conditions along with thyroid symptoms may need supplemental help initially to boost mineral levels and cellular healing. Micronutrient testing is helpful to determine which supplements are helpful and what dosage is required.  
  • Ashwagandha is an adaptogenic herb that has been demonstrated to support the endocrine system, boosting thyroid hormone production while reducing cortisol. It's often recommended for those dealing with chronic stress and inflammation as part of their thyroid disease management.
  • Probiotic supplementation also has been shown to have beneficial effects on thyroid hormones and thyroid function in general and can be particularly effective for those in whom gut dysbiosis is present as a contributing factor to thyroid dysfunction.  
  • Omega-3 supplements can help reduce inflammation related to thyroid disease; studies show consumption of quality omega-3 fats enhances thyroid function.
  • Curcumin may help reduce inflammation and nodule size as a strategy to support thyroid health. A combination of spirulina-curcumin-Boswellia has shown to be effective in reducing the size of benign thyroid nodules and can be safely administered in the doses used in the presented clinical study.
  • Magnesium can benefit those dealing with hypothyroidism and Hashimoto's, as low magnesium levels have been linked to a higher rate of thyroid antibodies and hypothyroidism.  

*A note of caution: while iodine is a supplement often marketed for thyroid health, those with autoimmune thyroid conditions, in particular, should exercise caution with iodine in supplement form, as it can often worsen Hashimoto's symptoms or cause fluctuating thyroid hormone levels.

*Talking to your doctor before starting any supplements or herbs is important.

3: Switching to Non-Toxic Products

A long list of environmental factors has been shown to contribute to thyroid dysfunction, including:

  • Organochlorine pesticides
  • Chemicals such as bisphenol-A (BPA), triclosan, perchlorates, PCBs, and PBDEs
  • Certain cosmetics
  • Heavy metals, like cadmium and lead

Switching to non-toxic cleaning and beauty products, opting for organic produce when possible (and washing produce well, regardless), ventilating your home, and using air purifiers are all strategies to help reduce toxic exposure for those healing from thyroid disease. Evaluating for heavy metals and environmental toxins can help determine if this needs to be a priority in each case.  

4: Reducing & Managing Stress

When you're chronically stressed, you're more likely to develop autoimmune thyroid conditions and exacerbate existing thyroid problems. Learning how to reduce and manage existing stress is a crucial component of a functional medicine approach to thyroid disease. Exercise, yoga, meditation, and journaling are all methods that can help with stress management. Surrounding yourself with positive, supportive people also helps reduce stress.

5: Good Sleep Hygiene

Both hypothyroidism and hyperthyroidism can impact sleep, so creating a good sleep hygiene routine can be helpful. Reducing exposure to screens in the evening, ensuring your bedroom is dark, cool, and quiet, and keeping a regular bedtime are all ways to help improve sleep.

6: Balanced Exercise

Movement is an important component of optimal thyroid health and can help increase energy levels and reduce inflammation. For those actively dealing with thyroid disease, a balance of weight training and cardiovascular exercise, in addition to low-level movements like walking and yoga, can benefit thyroid health.

Too much high-intensity exercise may impede thyroid healing, so working with your doctor and a fitness professional can help create an exercise routine to suit your needs.

Is it Possible to Stop or Avoid Thyroid Medications?

For some individuals, medication can provide a bridge to healing while working on the underlying root causes of thyroid disease. Once thyroid function is normalized, individuals may be able to go off their medication under the guidance of their prescribing doctor. In some cases, such as surgical removal and radiation, thyroid hormone replacement must be lifelong.

Therapeutic interventions to support the thyroid can also impact the dosage of thyroid hormone needed, so it's essential to work with a practitioner and discuss any nutrition and supplemental changes with your prescribing doctor.

Additionally, working with a functional medicine practitioner to be proactive and look at optimal lab values can help identify subclinical thyroid dysfunction. In these cases, supporting the thyroid with nutrition, lifestyle changes, stress management, and targeted supplements can help regulate thyroid function without medication.

For those individuals who have felt like they have symptoms of hypo or hyperthyroid but were told their "labs are normal," subclinical thyroid dysfunction may be present and can be addressed using functional medicine strategies.


Thyroid conditions are increasingly common today, impacting women more often than men. There can be a variety of underlying root causes contributing to thyroid disease, including inflammation, gut dysbiosis, autoimmune disease, environmental toxin exposure, chronic stress, and more. Evaluating the body as a whole, rather than solely focusing on TSH, can help determine what nutritional, supplemental, and lifestyle changes can support healing from thyroid disease and reducing symptoms.

The information provided is not intended to be a substitute for professional medical advice. Always consult with your doctor or other qualified healthcare provider before taking any dietary supplement or making any changes to your diet or exercise routine.
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