Clinical review: The thyroid in mind: cognitive function and low thyrotropin in older people

Thyroid and aging or the aging thyroid? An evidence-based analysis of the literature

Thyroid hormone production, metabolism, and action change with aging. The reference ranges for serum thyrotropin and thyroid hormones are derived mainly from younger populations. Thus, the prevalence of subclinical thyroid dysfunction is increased greatly in the elderly. However, it is unclear whether mild thyroid dysfunction in the elderly is associated with adverse outcomes. In this review, we discuss current evidence-based literature on thyroid function in the elderly and whether subclinical thyroid dysfunction in the elderly should be treated.

Thyroid dysfunction in the elderly

Thyroid dysfunction is common in the general population, and mild or subclinical forms can be present in more than 10% of individuals aged >80 years. The diagnosis of abnormal thyroid hormone concentrations in people aged >60 years poses a challenge, as the clinical presentation of thyroid dysfunction is usually nonspecific, and ageing is associated with a number of physiological changes that can affect thyroid function test results. Furthermore, the presence of acute or chronic nonthyroidal illnesses and the use of medications that interfere with thyroid function tests are common confounders in the determination of thyroid status in the elderly. Early diagnosis and treatment of overt thyroid dysfunction is crucial in this population in view of the marked effects of abnormal circulating thyroid hormone levels on a number of organ systems, including the heart, the skeleton and the neurological system. The clinical significance of mild thyroid overactivity and underactivity remains uncertain, and the need for treatment of subclinical thyroid dysfunction is much debated. A number of large epidemiological studies have identified associations between mild thyroid dysfunction and short-term as well as long-term adverse outcomes, and a small but increasing number of randomized controlled intervention studies have been reported. Guidelines recommend treatment of thyroid dysfunction on the basis of the degree of abnormal serum TSH concentrations, patient age and associated comorbidities. This Review describes the current evidence on the prevalence, diagnosis, management and long-term consequences of thyroid dysfunction in the elderly.

TSH - Clinical Aspects of its Use in Determining Thyroid Disease in the Elderly. How Does it Impact the Practice of Medicine in Aging?

The last four decades have seen enormous growth in the efficacy of serum thyroid stimulating hormone (thyrotropin, TSH) assay methodology, establishing TSH as the hallmark of thyroid testing. At the center of the considerations is the strong inverse correlation between serum thyrotropin and free thyroxine concentrations. While it is widely accepted that elevated serum TSH concentrations are consistent with thyroid dysfunction, a vast multitude of additional factors must be considered before an accurate clinical diagnosis can be made followed by an appropriate treatment. Epidemiological studies have demonstrated slightly elevated serum TSH concentrations among the elderly population. There is, however, a debate whether these elevated TSH levels reflect an increased prevalence of hypothyroidism among the elderly or a normal aspect of healthy aging. A comprehensive analysis of the many variables associated with this debate and TSH measurement as a diagnostic tool in aging should provide insight into the clinical efforts to diagnose and treat thyroid disease, particularly in the elderly population.