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A Root Cause Medicine Approach to Euthyroid Sick Syndrome

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A Root Cause Medicine Approach to Euthyroid Sick Syndrome

Euthyroid sick syndrome is a condition where your thyroid functions normally, but your thyroid levels show up as abnormal. What causes this? Turns out a lot of different things – from severe liver and kidney disease to anorexia. 

For patients with this disorder, treating the underlying cause is the key to its resolution. In this article, we will discuss what euthyroid sick syndrome is, what causes it, its clinical features, and how to treat it holistically based on the underlying disease state. 


What is Euthyroid Sick Syndrome?

Euthyroid sick syndrome (ESS), also known as non-thyroidal illness syndrome, is a state wherein the levels of thyroid hormones in the blood are unusually low, yet the thyroid gland is functioning normally. This occurs in patients suffering from systemic illnesses that are not related to the thyroid. The unique feature of this syndrome is that, while thyroid hormone levels are decreased, the affected individual remains euthyroid, meaning their thyroid is operating in a normal capacity.

Diagnosing ESS is primarily based on ruling out hypothyroidism. The treatment focus is predominantly on managing the root illness. Significantly, despite the low levels of thyroid hormones, replacement with thyroid hormones is not warranted in these patients (1). 

Euthyroid Sick Syndrome Signs & Symptoms

ESS is observed in patients with a range of acute or chronic non-thyroid disorders (1).

The thyroid function test results of these patients might show abnormalities despite them having a functioning thyroid gland.

Thyroid Function Abnormalities:

  • Decreased T3 Levels: This is the most common anomaly. Decreased T4 Levels: Observed in patients with more severe or prolonged illness.
  • Increased rT3 Levels: A prominent feature in ESS.
  • TSH Levels: These might be within the normal range or even on the lower side. However, during the recovery phase, they might be slightly higher than normal.

Clinical Features:

  • Hypothermia: A low body temperature that can be life-threatening.
  • Hypoventilation: Decreased breathing rate.
  • Hypotension: Low blood pressure.
  • Lethargy: A state of fatigue or sluggishness.
  • Coma: A profound state of unconsciousness.

Euthyroid Sick Syndrome Underlying Causes

Euthyroid sick syndrome is associated with a myriad of critical illnesses. Conditions like pneumonia, anorexia nervosa, sepsis, significant trauma including hip fractures, cardiopulmonary bypass, myocardial infarction, malignancies, burns, organ transplantations, congestive cardiac failure, hypothermia, and cirrhosis have been linked to its onset. Additionally, medical interventions such as major surgeries can act as triggers (1,2).   

Recently, there's been an observed connection between this syndrome and Covid-19, especially with the discovery that low T3 levels in affected patients serve as an early indicator of poor prognosis. Other disorders that might lead to abnormal thyroid function test results pointing towards this condition encompass chronic kidney disease, diabetic ketoacidosis, drug overdose, and severe fasting (1,2).  

Functional Medicine Labs to Test For The Root Cause Of Euthyroid Sick Syndrome

Functional medicine labs offer a variety of tests that can help tailor treatment to patients, allowing providers to optimize management strategies.

Thyroid Function Panel

A Comprehensive Thyroid Function Panel will measure markers such as T3, T4, reverse T3 (rT3), TSH, and thyroid antibodies. Given that ESS is characterized by abnormal thyroid function in the context of a non-thyroidal illness, it's critical to assess the overall function of the thyroid. This test provides insight into how the thyroid is producing and converting its hormones.

In ESS, you would expect to see TSH <10 mlU/L (usually low to slightly elevated) but not high as is usual in primary hypothyroidism. In addition, serum rT3 will be elevated, and T3 will be low (1,2). 

Comprehensive Metabolic Panel (CMP)

Many of the conditions linked to ESS, such as starvation, anorexia nervosa, sepsis, diabetic ketoacidosis, and cirrhosis, are metabolic in nature. A CMP is a blood test that gives doctors a big-picture look at the body's chemical balance and metabolism. It measures glucose, calcium, and electrolytes, hence giving indications about kidney and liver function, as well as electrolyte and fluid balance. If desired and depending on the underlying cause of the disease, practitioners can dive deeper with testing, such as a renal panel or a liver function panel (1,2). 

Cardiac Health Panel

Given the association between ESS and cardiovascular conditions like myocardial infarction and congestive cardiac failure, assessing heart health may be indicated based on the patient’s history and clinical picture. This panel additionally includes hs-CRP, which is a great marker of inflammation in the body (1,2).  

Serum Cortisol

Serum cortisol is often elevated in ESS, which can make it a distinguishing factor against hypothyroidism (which is usually low or low-normal in those patients) (1). 

Conventional Treatment for Euthyroid Sick Syndrome

Conventional treatment for ESS focuses on the resolution of the underlying disease or disorder (1,2). 

Functional Medicine Treatment for Euthyroid Sick Syndrome

Functional medicine treatment for ESS focuses on addressing the root cause of the condition. Recognizing that every disease is influenced by holistic factors, this approach emphasizes improving nutrition, incorporating relevant supplements and herbs, and including therapies to manage stress to create a comprehensive healing environment for the patient. This personalized method ensures that treatment aligns with individual needs for optimal health outcomes.

Nutrition for Euthyroid Sick Syndrome

As many different diseases and disorders can trigger ESS, nutrition guidelines are based on the cause. However, generally speaking, the diet should focus on a variety of nutrient-dense whole foods in order to promote overall health.

Some of the healthiest diets include the Mediterranean diet and the anti-inflammatory diet. Both of these would make great general choices for patients with ESS. For patients with cardiac abnormalities causing their symptoms, the DASH diet may also be recommended. 

Supplements & Herbs for Euthyroid Sick Syndrome

Like nutrition, recommended supplements and herbs depend on the underlying cause. For patients with cardiac conditions, supplements like omega-3s or green tea may help improve heart health. For patients with kidney disease, supplements such as vitamin D or probiotics may be indicated. For patients with liver abnormalities, supplements like milk thistle or vitamin E may promote liver health. For disorders related to increased inflammation, supplements such as ginger or turmeric may help reduce one’s inflammatory load (10). 

Complementary and Integrative Medicine for Euthyroid Sick Syndrome

Complementary and integrative medicine therapies may help to reduce symptomatology. Generally speaking, active disease, especially when chronic, can cause increased stress on the body. Therefore, therapies aimed at reducing stress may help patients with ESS, as underlying disease states influence the development of this disorder.

Mind-body therapies, such as yoga, meditation, and slow breathing exercises, offer effective, natural stress-reduction techniques supported by functional medicine. These practices promote physical and mental well-being, with studies highlighting their ability to improve sleep, reduce cortisol levels, and stimulate the body's "rest-and-digest" response. 

Incorporating regular physical activity into one's routine can also play a pivotal role in managing cortisol levels and enhancing sleep quality as well. Exercise regimens should be tailored based on the patient and underlying disease states causing ESS.  



In summary, euthyroid sick syndrome is a multifaceted condition with a myriad of potential triggers. While traditional treatments emphasize addressing the primary disease, a functional medicine approach provides a holistic perspective, targeting nutrition, stress management, and complementary therapies to support overall wellness. Understanding and diagnosing ESS is paramount to guide effective treatment strategies. Individualized care, rooted in both conventional and functional medicine, offers patients the best chance at achieving optimal health outcomes.

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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Lab Tests in This Article


  1. B. (n.d.). Euthyroid Sick Syndrome - Endocrine and Metabolic Disorders - Merck Manuals Professional Edition. Merck Manuals Professional Edition.
  2. Ganesan, K., Anastasopoulou, C., & Wadud, K. (2022, December 8). Euthyroid Sick Syndrome - StatPearls - NCBI Bookshelf. Euthyroid Sick Syndrome - StatPearls - NCBI Bookshelf.
  3. Rupa Health. (2023, April 25). Rupa Health.
  4. Rupa Health. (2023, May 10). Rupa Health.
  5. Rupa Health. (2023, April 6). Rupa Health.
  6. Rupa Health. (2023, May 19). Rupa Health.
  7. Rupa Health. (2021, December 7). Rupa Health.
  8. Rupa Health. (2023, July 5). Rupa Health.
  9. 4 Science Backed Health Benefits of The Mediterranean Diet. (2022, November 16). Rupa Health.
  10. Rupa Health. (2023, May 22). Rupa Health.
  11. Rupa Health. (2022, September 16). Rupa Health.
  12. Rupa Health. (2023, May 18). Rupa Health.
  13. Rupa Health. (2023, March 28). Rupa Health.
  14. Rupa Health. (2023, June 28). Rupa Health.
  15. Thau, L., Gandhi, J., & Sharma, S. (2022, August 29). Physiology, Cortisol - StatPearls - NCBI Bookshelf. Physiology, Cortisol - StatPearls - NCBI Bookshelf.
  16. Rupa Health. (2023, April 14). Rupa Health.
  17. The effects of physical activity on cortisol and sleep: A systematic review and meta-analysis - PubMed. (2022, September 1). PubMed.
  18. Cloyd, Dr. J. (2023a, May 24).
  19. Decesaris, Dr. L. (2022, August 8). Worried About Your Thyroid Health? Ask Your Doctor For These 3 Thyroid Labs. Rupa Health.
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