woman self-checking thyroid health

Thyroid Testing Limitations — Is It Actually Helpful?

By Dr. Benjamin Busch, DO

Your thyroid gland is a small but mighty organ that is located in your throat. The thyroid gland plays an important role in maintaining your overall health and well-being. This gland is responsible for producing hormones in the regulation of your body temperature, metabolism, and energy levels. Therefore, thyroid’s impact on the body cannot be overlooked.

Since thyroid glands play a significant role in health maintenance, assessment of their functions is a fundamental aspect of healthcare. Traditional thyroid tests involve the evaluation of levels of thyroid-stimulating hormones (TSH), T3, and T4 in the blood. It is the prescribed method for diagnosing various disorders related to the thyroid. 

However, with the advancements in the field of medicine, the reliability and effectiveness of these standard tests have become a query. In this article, we will learn about the complexities of thyroid function and the limitations of thyroid blood tests. We will find out why you can only partially rely on TSH, T3, and T4 levels to get a complete picture of your thyroid health. 

Understanding the complexity of thyroid function

In order to rule out an appropriate method for diagnosing thyroid problems, it is critical to understand the complexity of thyroid function which lies in the interplay among the thyroid hormones and the feedback mechanisms of the body. Basically, your thyroid gland produces two important hormones called Thyroxine (T3) and Triiodothyronine (T4). These hormones are responsible for carrying out the most vital functions of the thyroid. T4 is produced in abundance and it serves as a precursor to T3. T3 is the more potent form of a hormone that plays a significant role in energy production and metabolism. But the plot thickens, Reverse T3, an isomer of T3, which has a similar shape but different orientation, is formed when the body is exposed to chronic stress. (A good example of an isomer can be found looking at the difference between “W” and “M”). Reverse T3 has a similar shape but actually competes to block the function of T3, and can be a sign of developing adrenal fatigue.

The pituitary gland secretes Thyroid Stimulating Hormone (TSH) which controls the production of T4 by the thyroid gland. 

As the name suggests, the TSH released into the bloodstream by the pituitary glands stimulate the production of Thyroid hormones when they are required. When there are sufficient levels of T3 and T4 in the body, the pituitary glands reduce the production of TSH, signaling the thyroid gland to slow down the production of thyroid hormones.

The thyroid is like the gas pedal of your metabolism.

The thyroid gland produces hormones that strongly influence metabolism. T3 and T4 hormones impact:

  • energy production
  • protein synthesis
  • fat metabolism
  • body temperature
  • cardiovascular function
  • growth

Hypothyroidism (underactivity) slows metabolism, while hyperthyroidism (overactivity) speeds it up. The hypothalamus and pituitary gland regulate thyroid hormone production through a feedback loop. Disruptions in this process can affect metabolism and other bodily functions.

Learn more about how thyroid health directly influences metabolism.

Assessment of thyroid function

Standard thyroid blood tests involve measuring the levels of TSH, T3, and T4 in the blood to assess the functionality of the thyroid. If the levels of TSH are increased, the condition is called hypothyroidism which is an indication of underactive thyroid. An underactive thyroid means that the thyroid gland is not producing a sufficient quantity of thyroid hormones. As a result, the pituitary glands have to stimulate the underactive thyroid by producing more than the normal amount of TSH. On the other hand, if the levels of TSH are low, this indicates an overactive thyroid, and the condition is medically termed hyperthyroidism. This approach for assessing thyroid functions has been in practice for decades. 

However, according to recent research studies, the thyroid functions of an individual can not be accurately represented by solely relying on the levels of TSH, T3, and T4 hormones in the blood. For example, some people may have many symptoms of hypothyroidism and have a “normal” TSH within the wide acceptable range, and adequate T3 and T4 hormones. This represents a condition called subclinical hypothyroidism in which the patients may experience the symptoms of hypothyroidism while the blood test shows normal levels of thyroid hormones. Their provider might not have checked a Reverse T3 to find that the body is actually blocking T3 function because of stress, and may need support for the tired adrenal glands.

Moreover, the reference ranges for TSH, T3, and T4 hormones vary among various laboratories which leads to discrepancies in the interpretation of results. In addition, several factors such as age, gender, and underlying health condition also influence the levels of thyroid hormones. Therefore, establishing a universal standard for “normal” levels is no less than a challenge.

What are the symptoms of Thyroid Dysfunction?

Thyroid dysfunction can be associated with various symptoms depending on whether the thyroid is underactive or overactive. If the thyroid is underactive, the condition is diagnosed as hypothyroidism.

Hypothyroidism is often characterized by some common symptoms which are as follows:

  • Weight gain
  • Weakness and fatigue
  • Dryness of skin and hair
  • Depression and irritability
  • Sensitivity to low temperature
  • Joint pain
  • Muscle aches
  • Cognitive issues 
  • Constipation
  • Hair loss
  • Menstrual irregularities

On the contrary, an overactive thyroid leads to a condition termed hyperthyroidism which is characterized by the following symptoms:

  • Increased appetite
  • Unintentional weight loss
  • Excessive sweating 
  • Intolerance to heat
  • Irregular or rapid heartbeat
  • Anxiety
  • Nervousness
  • Changes in menstrual patterns
  • fatigue
  • Diarrhea
  • Sleeping difficulty
  • Tremors in hands

Although these symptoms are commonly associated with Thyroid Dysfunction, remember that they are not specific to Thyroid Dysfunction. This means that it might be possible that the underlying cause of any of these symptoms is another health-related issue. However, it is important to notice that these symptoms play a significant role in the diagnosis of Thyroid Dysfunction.

Why is TSH testing considered inadequate?

TSH testing has been a go-to method for assessing thyroid function for ages. As discussed earlier, a higher level of TSH in blood indicates hypothyroidism and a lower level is an indication of hyperthyroidism. This very simple approach for testing thyroid function has the potential for misdiagnosis leading to inadequate treatment for patients with thyroid problems.

One major reason behind the limitation of TSH testing is subclinical hypothyroidism.

It is a condition in which the levels of thyroid stimulating hormone (TSH), T3 and T4 appear to be normal, yet the patient experiences the subtle symptoms of hypothyroidism such as fatigue, sensitivity to colds, and weight gain. Subclinical hypothyroidism, in easy words, is an unnoticed form of underactive thyroid function that can lead to serious health issues if left untreated. This condition is also an indication of the fact that TSH testing is not an adequate approach for assessing thyroid function as it may neglect minor Thyroid Dysfunction leading to misdiagnosis. 

The accuracy and effectiveness of TSH testing have become the topic of debate and increased inquiry in the world of medicine. 

Are there any limitations of T3 and T4 testing?

“Low thyroid function is the single primary reason people feel tired, get diseased, and age prematurely. And yet the blood tests that doctors use to diagnose it are the most unreliable tests in all of medicine. — Dr. Frank Shallanberger 

Certain limitations are associated with T3 and T4 tests while evaluating thyroid functionality. One of the major barriers is that the levels of T3 and T4 hormones tend to fluctuate throughout the day. Furthermore, the levels of thyroid hormones also vary among individuals. 

Therefore, it is understood that unlike TSH, which is comparatively stable and measured quite easily, the levels of T3 and T4 can alter significantly over short periods. That is why establishing a standard reference range for these hormones is pretty challenging. Relying solely on measuring the Levels of thyroid hormones for evaluation of thyroid function may lead to failure in diagnosing Thyroid Dysfunction.  

In addition, there are many factors that influence the levels of thyroid hormones. These factors include your age, your gender, and any health issue that you might be facing. It is also important to realize that the hormonal profile of every individual is unique which again makes it difficult to set a universal range for hormone levels. 

The importance of symptomatic diagnosis of Thyroid Dysfunction

Symptomatic diagnosis of Thyroid Dysfunction plays a significant role in effectively addressing and identifying thyroid-related disorders. Thyroid issues are often associated with distinct signs and symptoms. Understanding these symptoms is quite helpful for healthcare experts to diagnose the condition on the basis of subtle signs, even before the manifestation of lab test results. 

Symptomatic diagnosis of Thyroid Dysfunction is a proactive approach to identifying abnormal thyroid conditions. This approach allows for timely interventions and preventive measures while reducing the risk of possible complications. 

Furthermore, symptomatic diagnosis also enables healthcare professionals to easily differentiate between hypothyroidism and hyperthyroidism, allowing the selection of appropriate medications and treatment as per the patient’s requirements.  

In many cases, the symptoms of Thyroid Dysfunction are very common medical signs and symptoms. Thryoid-related conditions can be associated with a wide array of emotional, physical, and cognitive changes. A detailed assessment of these symptoms allows medical practitioners to consider individual patient experiences. This is particularly important for designing a personalized approach toward treatment strategies. 


The reliability of conventional thyroid blood tests in accurate diagnosis of thyroid issues has been brought into question. While TSH testing has been serving as a gold standard test for the evaluation of thyroid function, it is also important to remember that it might not be able to provide a comprehensive view of thyroid function. 

Subclinical hypothyroidism highlights the inadequacy of solely relying on TSH tests. Individuals with subclinical hypothyroidism show mildly elevated or “normal” levels of TSH while their T3 and T4 levels appear to be within the normal range. This confusion may even result in neglecting patients who require a thyroid replacement. Plus, the fluctuations in T3 and T4 levels throughout the day and their variation among individuals is yet another factor that makes it a challenge to establish a standard reference range for hormone levels that works universally. 

Symptomatic diagnosis of Thyroid Dysfunction emerges as a crucial aspect of effective thyroid assessment. Understanding the diverse range of symptoms associated with thyroid issues empowers healthcare professionals to identify subtle signs early on, enabling timely care to help people feel better.

This article emphasizes the importance of symptomatic diagnosis of thyroid function. This requires an understanding of the diverse range of symptoms associated with Thyroid Dysfunction. Recognizing thyroid symptoms at an early stage allows for timely diagnosis and treatment. Furthermore, patient-centered or personalized care approach helps in carrying out better communication between patient and medical practitioner which is particularly helpful in designing individual treatment strategies.

Last but not least, a combination of symptomatic evaluation with thyroid blood tests is important for a more effective and accurate understanding of thyroid health. This allows for a proper diagnosis and better care, ultimately leading to improvement in the patient’s overall well-being.

This content is adapted from an article written by Dr. Frank Shallenberger, “Thyroid blood testing is useless.”

Dr. Frank Shallenberger is the Editor-in-Chief of Second Opinion Newsletter and Second Opinion Health Alert. Dr. Shallenberger earned his medical degree from the University of Maryland School of Medicine and received his postgraduate training at Mt. Zion Hospital in San Francisco. Dr. Shallenberger is board certified by the American Board of Anti-Aging Medicine and has been practicing medicine for over 44 years.

Dr. Shallenberger created Bio-Energy Testing, Che-Zone, and Prolozone Therapy and has trained more than 700 doctors in the use of these techniques. He is the founder and director of The Nevada Center of Alternative & Anti-Aging Medicine and previously worked as a clinical Instructor of Family Medicine at the U.C. Davis School of Medicine. Dr. Shallenberger is the author of three books, Bursting with Energy, The Type 2 Diabetes Breakthrough, and The Ozone Miracle.

Dr. Shallenberger is the president of the Nevada State Homeopathic and Integrative Medicine Association, the past president of the American Academy of Ozone Therapy, and was appointed by the governor of Nevada to serve on the Nevada State Board of Homeopathic Medical Examiners. He has served as a founding board member of the International Bio-Oxidative Medical Foundation and as a board member of the Society for Orthomolecular-Health Medicine.

Dr. Shallenberger also uses his knowledge and experience in the medical field to research and provide specialized formulations for Advanced Bionutritionals® Nutritional Supplements and Nutraceuticals. Advanced Bionutritionals is a cutting-edge line of vitamins and nutraceuticals. These high-quality supplements are made to assure purity and potency.


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