Thyroid function and aging

Thyroid activity changes as people age — the organ slowly becomes less active (1).

Aging-related changes in the thyroid

Several changes in the thyroid are likely to occur with age (2–6):

  1. The thyroid becomes smaller and harder to feel in the neck
  2. TPO and Tg antibodies (a sign of Hashimoto’s) become more frequent over the age of 60
  3. Iodine levels (a necessary component of thyroid hormones) are lower than they used to be
  4. It takes a long time for the body to produce T3 and T
  5. It takes longer to clear T4 from the body
  6. rT3 increases with age
  7. The daily 24 hour rhythm of TSH production — which is present from the birth on — starts fading

Thyroid hormone reference ranges for people over 70

The reference interval for TSH in the elderly is up to 7.5 mIU/L (7). TSH is a main thyroid hormone to be checked when assessing thyroid function.

T4 levels can be higher, while T3 reference ranges can be lower compared to the reference ranges for people who are middle-aged and younger (8, 9). Low selenium levels also correlate with low thyroid function (10).

Hypothyroidism in people over 70

An underactive thyroid is more common in people in their 70s than in any other age group (1). With age, here is an increase in the number of people diagnosed with autoimmune diseases (11, 12).

Diagnosing an underactive thyroid in people over 70

Symptoms of an underactive thyroid overlap with symptoms aging, which might cause a delay in diagnosis (1, 11).
The most common hypothyroid symptoms for elderly people include (13–15):

  • Fatigue
  • Weakness
  • Dry skin
  • Poor memory

Hypothyroidism treatment for people over 70

Older patients are more sensitive to thyroid hormone replacement therapy. There are several things to consider (16, 17):

  • Problematic interactions with other medications, especially for chronic illnesses
  • Different speed of thyroid hormone clearance, which might lead to an increase in T4 levels
  • Overtreatment might worsen existing heart problems and lead to new health problems, such as an irregular heart beat (arrhythmia) and progressive bone loss
  • Estrogen replacement therapy in postmenopause might lead to a need for a higher dose of T4 therapy

How we write: our information is based on the results of peer reviewed studies using the National Library of Medicine platform. It is written by scientists and reviewed by external experts. If you believe we might have overseen crucial scientific information, please contact us at

Disclaimer: This information is not intended to mitigate, prevent, treat, cure or diagnose any disease or condition. If you want to change your treatment, lifestyle, your diet, include supplements in your diet or have concerns about your health, please consult your doctor before trying new approaches.


  1. Levy EG. Thyroid disease in the elderly, 1991
  2. Irvine RE. Thyroid disease in old age, 1973
  3. Mariotti S, et al. The aging thyroid, 1995
  4. Hollowell JG, et al. Iodine nutrition in the United States. Trends and public health implications: Iodine excretion data from National health and nutrition examination surveys I and III (1971–1974 and 1988–1994), 1998
  5. Ajish TP, et al. Geriatric thyroidology: An update, 2012
  6. Bensenor IM, et al. Hypothyroidism in the elderly: diagnosis and management, 2012
  7. Surks MI, et al. Age-specific distribution of serum thyrotropin and antithyroid antibodies in the US population: implications for the prevalence of subclinical hypothyroidism, 2007
  8. Lipson A, et al. A study of age-dependent changes in thyroid function tests in adults, 1979
  9. Hershman JM, et al. Serum thyrotropin and thyroid hormone levels in elderly and middle-aged euthyroid persons, 1993
  10. Olivieri O, et al. Low selenium status in the elderly influences thyroid hormones, 1995
  11. Kim MI. Hypothyroidism in Older Adults, 2020
  12. Díez JJ. Hypothyroidism in patients older than 55 years: an analysis of the etiology and assessment of the effectiveness of therapy, 2002
  13. Doucet J, et al. Does age play a role in clinical presentation of hypothyroidism, 1994
  14. Mokshagundam S, et al. Thyroid disease in the elderly, 1993
  15. Mitrou P, et al. Thyroid disease in older people, 2011
  16. McDermott MT, et al. Management practices among primary care physicians and thyroid specialists in the care of hypothyroid patients, 2001
  17. Arafah BM. Increased need for thyroxine in women with hypothyroidism during estrogen therapy, 2001

Photo: Unsplash; Design: VLM Health



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