Clinical Thyroidology® for the Public
Summaries for the Public from recent articles in Clinical Thyroidology
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THYROID FUNCTION
Thyroid function has no impact on physical activity in individuals aged 46-89 years
BACKGROUND
Thyroid hormone has an important role in regulating the body’s metabolism. When thyroid hormone levels are low, metabolism slows down, energy is decreased and patients may gain weight and have a slow heart rate. This is usually reversed when thyroid hormone levels return to normal by treatment with levothyroxine. When thyroid hormone levels are high, metabolism speeds up, energy may be initially increased and patients may lose weight and have a fast heart rate. Muscle weakness can develop if thyroid hormone levels are either too high or too low.
The effects of thyroid hormone on muscle tissue and the heart have been studied in details. One question of interest has been the connection between the level of thyroid hormones and the rate of physical activity. However, most of the previous research in this topic has been done in athletes and military personnel, both of whom are physically fit.
The aim of this study is to investigate the connection between the thyroid function and physical activity over time in general population.
THE FULL ARTICLE TITLE
Dueñas OHRD et al. 2020 Thyroid function and physical activity: A population-based cohort study. Thyroid. Epub 2020 Dec 23. PMID: 33198599.
SUMMARY OF THE STUDY
The study was done in the Netherlands.
The participants had been already registered to be part of a large ongoing study (Rotterdam Study) initiated in 1989; all of them were 45 years or older. The original number of participants in Rotterdam study is over 7,000; however, in the current study, only individuals (2470) with thyroid function studies were included (TSH, Free T4 and Thyroid Peroxidase antibodies). The participant’s physical activity was assessed by a validated questionnaire, which obtained once in 2006 to 2008 and again 2008 to 2013.
The average age of participants was 57.3 years and 58% were women. The average TSH was 2.04 mIU/L (normal range: 0.4 to 4.0). The average of Free T4 was 1.21 ng/ dL (normal range: 0.85 to 1.95). The result of the study showed no association between the physical activity and the levels of TSH, Free T4 or thyroid peroxidase antibodies.
WHAT ARE THE IMPLICATIONS OF THIS STUDY?
This study showed no impact from thyroid function on physical activity in middle-aged to old individuals from the general population. However, they only obtained information regarding physical activity duration not intensity of exercise, so that still needs to be studied. Finally, they did not separate out patients that were on levothyroxine because their thyroid hormone levels were too low. This would be an interesting future study.
— Shirin Haddady, MD, MPH
ATA THYROID BROCHURE LINKS
Thyroid Function Tests: https://www.thyroid.org/thyroid-function-tests/
Thyroid Hormone Treatment: https://www.thyroid.org/thyroid-hormone-treatment/
Hypothyroidism (Underactive): https://www.thyroid.org/hypothyroidism/
ABBREVIATIONS & DEFINITIONS
Hypothyroidism: a condition where the thyroid gland is underactive and doesn’t produce enough thyroid hormone. Treatment requires taking thyroid hormone pills.
Levothyroxine (T4): the major hormone produced by the thyroid gland and available in pill form as Synthroid™, Levoxyl™, Tirosint™ and generic preparations.
TSH: thyroid stimulating hormone — produced by the pituitary gland that regulates thyroid function; also the best screening test to determine if the thyroid is functioning normally.
Thyroxine (T4): the major hormone produced by the thyroid gland. T4 gets converted to the active hormone T3 in various tissues in the body.
Thyroid peroxidase antibodies: these are antibodies that attack the thyroid instead of bacteria and viruses, they are a marker for autoimmune thyroid disease, which is the main underlying cause for hypothyroidism and hyperthyroidism in the United States.
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