Subclinical thyroid dysfunction symptoms in older adults: cross-sectional study in UK primary care

BACKGROUND: Subclinical thyroid dysfunction - abnormal serum thyrotrophin (thyroid-stimulating hormone; TSH) concentrations with normal free thyroxine (FT4) is common in older people. It remains unclear whether individuals with subclinical serum status experience an increased symptom profile. AIM: To compare the prevalence of those symptoms typically associated with overt thyroid dysfunction in older individuals with a subclinical and euthyroid serum profile. DESIGN AND SETTING: Cross-sectional study, nested within the Birmingham Elderly Thyroid Study (BETS); from 19 UK general practices. METHOD: Adults living in a community setting (aged ≥65 years), without overt thyroid dysfunction or associated treatment, self-reported the presence or absence of 18 symptoms (while serum result naïve). Serum concentrations of TSH and FT4 were measured to establish thyroid status. RESULTS: A total of 2870 individuals were screened: 2703 (94%) were categorised as euthyroid (normal), 29 (1%) subclinically hyperthyroid, and 138 (5%) subclinically hypothyroid. Symptoms were common in all groups. No significant differences in the prevalence of individual symptoms were observed between the euthyroid and subclinically hypothyroid groups nor in comparison with the subclinically hyperthyroid group. Multivariate logistic regression analysis failed to reveal an association between individual or multiple symptoms and subclinical status. CONCLUSION: Findings suggest that subclinical thyroid dysfunction does not confer a symptom burden in older individuals and support adherence to guidelines in the non-treatment of subclinical thyroid dysfunction. GPs may use the findings to reassure older people presenting with symptoms that subclinical thyroid dysfunction is an unlikely explanation. The presence of persistently abnormal TSH concentrations may be linked to long-term risks of cardiovascular disease, especially atrial fibrillation, but whether this should prompt treatment and whether such treatment alters vascular outcomes is unknown.