Your Global Health Resource
Hypothyroidism is more frequent in older adults (third age)
1. Natural Aging of the Thyroid Gland
The thyroid undergoes structural and functional changes with age:
Reduced thyroid follicle number and vascular supply.
Increased fibrosis and lymphocytic infiltration.
These changes can impair hormone synthesis, especially in individuals with borderline thyroid function.
2. Higher Prevalence of Autoimmune Thyroiditis
Hashimoto’s thyroiditis, the most common cause of hypothyroidism in developed countries, becomes more prevalent with age.
The immune system becomes dysregulated with aging (“immunosenescence”), increasing the risk of autoimmune diseases.
3. Polypharmacy and Drug Effects
Older adults often take multiple medications that can affect thyroid function:
Amiodarone (antiarrhythmic)
Lithium (psychiatric use)
Interferons, tyrosine kinase inhibitors, glucocorticoids
These can inhibit thyroid hormone production or alter peripheral conversion of T4 to T3.
4. Blunted Clinical Presentation Leads to Underdiagnosis
Symptoms of hypothyroidism (fatigue, constipation, cold intolerance, depression) often overlap with normal aging.
This leads to late diagnosis or underdiagnosis, increasing its recorded prevalence as people age.
5. Changes in TSH Set Point
Aging may shift the normal reference range for TSH slightly upward.
Some individuals considered “subclinically hypothyroid” by younger standards may, in fact, reflect a normal variant in older adults.
6. Impact of Chronic Illness and Comorbidities
Chronic diseases such as cardiovascular disease, diabetes, and chronic kidney disease are common in the elderly and can impact thyroid metabolism or hormone binding.
Clinical Implication:
It’s essential to screen thyroid function in elderly patients with nonspecific symptoms or unexplained depression, fatigue, or cognitive decline.
TSH and free T4 should be part of routine geriatric assessment when clinically indicated.
