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Metabolic Syndrome’s Interference with Thyroid


Thyroid dysfunction is abnormal functioning of the thyroid gland. This can be portrayed as either an underactive (hypothyroid) or overactive (hyperthyroid) thyroid.

Thyroid Hormone Production in the HPA-T Axis

Thyroid hormone production begins with the hypothalamus, which releases thyrotropin-releasing hormone (TRH) to the pituitary gland. The pituitary gland then releases thyrotropin-stimulating hormone (TSH) to the thyroid gland. The thyroid gland then releases T4 and T3. Inactive T4 is converted to active T3, the thyroid hormone that controls metabolism.

Metabolic Syndrome and Other Thyroid Disorders

Metabolic Syndrome (MetS) can be described as the conglomeration of various conditions including insulin resistance, irregular blood glucose levels, excess body fat, abnormal cholesterol or triglyceride levels in the bloodstream, and dysfunction of the inner lining of the blood vessels. These factors increase the risk of heart disease, diabetes, and stroke. If at least three of the following risk factors are present in an individual, MetS may be diagnosed: [1]

  • Abdominal obesity (“apple shape” body type)
  • High blood pressure
  • High triglyceride level
  • Low HDL cholesterol level
  • High fasting glucose

Those with metabolic syndrome may be at higher risk for thyroid disorders, and vice versa. Most research has found links between decreased thyroid activity and metabolic syndrome.

TSH and Metabolic Syndrome

One study that analyzed over 7,000 euthyroid subjects found that increasing TSH concentrations significantly increased the number of components of MetS.[2]

Hypothyroidism and Obesity

Overt hypothyroidism (hypothyroidism with clear symptoms) is associated with weight gain or inability to lose weight. A cross-sectional study found that there is a positive association between obesity and subclinical hypothyroidism (hypothyroidism with mild symptoms). [3]

Insulin Resistance and Glucose Transport

Insulin resistance has also been linked to thyroid dysfunction. Studies have revealed that those with subclinical and overt hypothyroidism have higher baseline fasting glucose levels[4] and decreased glucose transport. [5] Though less clear in subclinical hypothyroid individuals, increased triglycerides were found in approximately 1/3 of all overt hypothyroidism patients. [6]


So, we see that MetS is associated with low thyroid function, which contributes to weight gain and therefore further insulin resistance. It is a vicious circle for which dietary, nutritional and even medical intervention is necessary if the circle is to be interrupted.

How To Improve Thyroid Function

Ways to improve thyroid function include:

  • Optimize iodine sufficiency (except in Hashimoto’s thyroiditis)
  • Optimize cofactor sufficiency: selenium, iron, vitamin A, zinc, copper
  • Avoid heavy use of goitrogens, such as soy and raw cruciferous veggies
  • Increase exercise
  • Correct hypoglycemia (not enough blood sugar to promote T4 conversion)



[1] National Heart, Lung, and Blood Institute. 2016. What is Metabolic Syndrome? Retrieved Aug 2, 2016 from

[2] Lee YK, Kim JE, Oh HJ, Park KS, Kim SK, Park SW, Kim MJ, Cho YW. Serum TSH level in healthy Koreans and the association of TSH with serum lipid concentration and metabolic syndrome.Korean J Intern Med. 2011;26:432–439.

[3] de Moura Souza A, Sichieri R. Association between serum TSH concentration within the normal range and adiposity. Eur J Endocrinol. 2011;165:11–15.

[4] Waring AC, Rodondi N, Harrison S, Kanaya AM, Simonsick EM, Miljkovic I, Satterfield S, Newman AB, Bauer DC. Thyroid function and prevalent and incident metabolic syndrome in older adults: the health, ageing and body composition study. Clin Endocrinol (Oxf) 2012;76:911–918.

[5] Maratou E, Hadjidakis DJ, Kollias A, Tsegka K, Peppa M, Alevizaki M, Mitrou P, Lambadiari V, Boutati E, Nikzas D, Tountas N, Economopoulos T, Raptis SA, Dimitriadis G. Studies of insulin resistance in patients with clinical and subclinical hypothyroidism. Eur J Endocrinol. 2009;160:785–790.

[6] Duntas LH, Brenta G. The effect of thyroid disorders on lipid levels and metabolism. Med Clin North Am. 2012;96:269–281.


Clinical Contributor

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Ramona Richard, MS, NC

Ramona Richard, MS, NC

Ramona Richard graduated with honors from the University of California with a Bachelor’s Degree in psychology and graduated summa cum laude with a Master’s Degree in Health and Nutrition Education. She also holds a Standard Designated Teaching Credential from the State of California, is a California state-certified Nutrition Consultant and a member of the National Association of Nutrition Professionals.

Ramona has participated in nutrition education in both public and private venues, including high school and college presentations, radio and public speaking for the past 20 years. She is the owner of Radiance, a nutrition consulting company, the Director of Education for Sanesco International, and a medical technical writer.

Disclaimer: The information provided is only intended to be general educational information to the public. It does not constitute medical advice. If you have specific questions about any medical matter or if you are suffering from any medical condition, you should consult your doctor or other professional healthcare provider.

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