From the Guidelines
TSH levels can be higher in elderly individuals compared to younger adults, with some healthy elderly people having TSH levels between 4-7 mIU/L that would be considered elevated in younger adults. The normal range for TSH tends to shift upward with age, due to several factors including reduced thyroid hormone metabolism, changes in the hypothalamic-pituitary axis, and decreased sensitivity to feedback mechanisms 1. However, it's essential to note that significantly elevated TSH levels (typically above 10 mIU/L) are not normal at any age and may indicate hypothyroidism requiring treatment. When evaluating TSH in elderly patients, doctors consider the individual's symptoms, other health conditions, and medication use rather than relying solely on reference ranges.
Some key points to consider when evaluating TSH levels in the elderly include:
- The high variability of TSH secretion levels and the frequency of reversion to normal thyroid function without treatment underscore the importance of not relying on a single abnormal laboratory value as a basis for diagnosis or the decision to start therapy 1.
- The annual number of dispensed prescriptions of levothyroxine sodium in the United States increased by 42% over a 5-year period, from 50 million in 2006 to 71 million in 2010, indicating a potential for overdiagnosis and overtreatment 1.
- Initiation and use of thyroid hormone therapy seem to be particularly common in older adults, with data from the CHS (Cardiovascular Health Study) showing a steady increase in the overall percentage of older adults receiving thyroid hormone therapy from 9% in 1989 to 20% in 2006 1.
Treatment decisions for borderline elevated TSH in the elderly are often more conservative, as mild TSH elevations may not require immediate thyroid hormone replacement unless symptoms are present or there are other compelling reasons for treatment. Clinicians should be aware of subtle signs of thyroid dysfunction, particularly among those at high risk, and evaluate for symptoms of hypothyroidism, while also considering the potential harms of overdiagnosis and overtreatment 1.
From the Research
Thyroid-Stimulating Hormone (TSH) Levels in the Elderly
- TSH levels have been demonstrated to increase with aging, regardless of the existence of an actual thyroid disease 2, 3.
- The reference range for TSH also rises with age, as the population distribution of TSH concentration progressively rises with age 4.
- There is evidence to suggest that minor TSH elevations are not associated with important outcomes such as impaired quality of life, symptoms, cognition, cardiovascular events, and mortality in older individuals 4.
Diagnosis and Treatment of Hypothyroidism in the Elderly
- The diagnosis of subclinical hypothyroidism (sHT) should be carefully verified to tailor an appropriate follow-up and ad hoc therapy, avoiding unnecessary or excessive treatment 2, 3.
- The treatment of choice for hypothyroid patients is hormone replacement with levothyroxine (LT4), but it is essential to consider multiple factors before commencing therapy, including age-dependent TSH increase, the presence of an actual thyroid disease, and comorbidities 2, 3, 5.
- The European Thyroid Association recommends treating elderly patients only when the TSH value is greater than 10 mU/l and the patient is symptomatic or has a high cardiovascular risk 5.
Age-Specific TSH Reference Ranges
- Establishing age-specific reference ranges for TSH in elderly individuals may aid in clinical decision-making and prevent overdiagnosis 6.
- Using age-specific TSH reference intervals may help identify meaningful subclinical hypothyroidism patients and reduce overdiagnosis and overtreatment of elderly subclinical hypothyroidism 6.