“Symptoms of hypothyroidism are nonspecific and poorly predict clinically significant thyroid dysfunction, especially in patients with underlying medical conditions and advanced age. Thus, it is essential to identify thyroid dysfunction before initiating therapy. Yet, it is estimated that about 30% of persons newly started on l-thyroxine treatment in the United States have normal thyroid function. When symptoms result in ordering thyroid function tests, an elevated thyroid-stimulating hormone (TSH) level should not trigger therapy without confirmatory TSH and free thyroxine (FT4) levels. Symptoms associated with overt hypothyroidism (elevated TSH, low FT4) usually resolve with l-thyroxine replacement, but therapy for subclinical hypothyroidism (low TSH, normal FT4), particularly in older patients, does not improve symptoms nor enhance quality of life. [..]
Age-, sex-, and race-adjusted reference intervals led to a decline in the frequency of most thyroid dysfunction diagnoses. Subclinical hypothyroidism declined in all age groups, and the decline was larger in women than in men. Exclusion of persons with thyroid peroxidase antibody positivity resulted in a reduction in the prevalence of subclinical hypothyroidism and subclinical hyperthyroidism, especially among patients older than 60 years. [..]
Samuels and colleagues reported that results of thyroid function testing within an age-adjusted laboratory reference range were not associated with variations in quality of life, mood, or cognitive function in community-dwelling older men. Without intervention, there was no change in these outcomes during 5 to 8 years of follow-up. These observations indicate that minor “elevations” of TSH do not document that thyroid dysfunction is the cause of nonspecific symptoms. Li and colleagues’ results show that age-, sex-, and race-based expected ranges for thyroid function tests should enhance our ability to identify clinically significant thyroid dysfunction, prescribe appropriate thyroid replacement therapy, and improve patient outcomes.”
Full article, JV Hennessey, Annals of Internal Medicine, 2025.5.6