Beyond the lab value: Why withholding thyroid treatment in older adults is often the best medicine
For decades, an abnormal thyroid lab result triggered an automatic reflex in many healthcare providers: prescribe thyroid hormone replacement. However, this standard remains controversial, as evidence suggests it may not be beneficial for older adults and favors a wait-and-see approach. Our recent paper explored the debated management of subclinical hypothyroidism in patients 65 and older.
The U.S. Preventive Services Task Force defines subclinical hypothyroidism as an elevated serum thyrotropin (TSH) level (greater than 4.5 mIU/L) with a normal free thyroxine (T4) level. Symptoms, if present, usually are mild and nonspecific. Interestingly, findings from the cross-sectional Colorado Thyroid Disease Prevalence Study revealed that these symptoms may be poor discriminators of thyroid dysfunction: While 25% of overt hypothyroid patients and 20% of individuals with subclinical hypothyroidism reported four or more hypothyroidism symptoms, 17% of individuals with normal thyroid reported the same symptom burden.
The TRUST trial offered other compelling evidence for the wait-and-see approach. While TSH levels successfully dropped into the normal reference range with treatment, they experienced no measurable clinical difference in hypothyroidism symptom scores or tiredness levels. This reinforces that biochemical changes on paper do not always translate to better patient well-being.
Are we treating a disease or a number?
Currently, the normal reference range for TSH is extrapolated from population-based data of healthy individuals. Yet, natural factors – including age, time of day, season and common medications – can easily alter TSH levels in adults.
A mildly elevated TSH level often is a completely normal part of aging. This forces a vital clinical question with ethical consequences: Are we treating a true illness or chasing a laboratory value?
The drive to aggressively normalize these lab values carries hidden dangers. Overtreatment can lead to thyrotoxicosis, heart risks and reduce bone density that can lead to fractures. Additionally, randomized clinical trials have not shown that medication improves quality of life or relieves symptoms for most older adults with mild cases (defined as TSH <10 mIU/L).
Embracing the “wait-and-see” approach
To protect patients from overtreatment, we advocate for a personalized “wait-and-see” approach. Because TSH levels fluctuate, we recommend retesting after two to three months. We also favor innovative and patient-centered strategies like the one proposed by the French Endocrine Society. They suggest dividing a patient’s age by 10 to establish a customized upper limit for normal TSH levels in those over 60. Under this age-based formula, an 80-year-old’s target TSH could safely be up to 8.0 mIU/L, rather than being held to the standard 4.5 mIUL cutoff used for younger populations.
Rethinking how we view subclinical hypothyroidism is a critical step toward truly personalized geriatric care. It requires us to step back, communicate openly with our patients about the risks of unnecessary medication, and embrace the fact that as our bodies age, our clinical definitions of “normal” should age right along with them.
By Drs. Risheng Xu, assistant professor, medicine – general internal medicine, Nalini Ram, professor, medicine – endocrinology, and Kristina Marie Little, assistant professor, medicine – geriatrics and palliative medicine
