Subclinical Hypothyroidism: is it Really Subclinical with Aging?

Area of Science:

• Endocrinology
• Geriatrics
• Clinical Medicine

Background:

• Subclinical hypothyroidism (SCH) diagnosis and management, particularly in older adults, requires updated clinical insights.
• Thyroid-stimulating hormone (TSH) measurement standards have evolved, necessitating a re-evaluation of diagnostic criteria.
• Limited recent research focuses on the clinical manifestations of SCH in elderly populations.

Purpose of the Study:

• To investigate the clinical features of subclinical hypothyroidism (SCH) in relation to age.
• To compare hypothyroidism-related clinical signs (hCS) between SCH and euthyroid states across different age groups.
• To evaluate the utility of hCS and TSH measurements in diagnosing thyroid dysfunction in older patients.

Main Methods:

• Prospective multicenter study conducted from 2012 to 2014.
• Inclusion of 807 subjects <60 years and 531 subjects ≥60 years.
• Monitoring of 11 hypothyroidism-related clinical signs (hCS), TSH, FT4, FT3, and anti-thyroperoxidase antibodies.

Main Results:

• In subjects <60 years, SCH was associated with an increased number and percentage of hCS.
• In subjects ≥60 years, hCS were not significantly different between SCH and euthyroid groups.
• In older individuals, only three hCS correlated with SCH and a decreased T3/T4 ratio, suggesting adaptive changes or reduced TSH activity.

Conclusions:

• Hypothyroidism-related clinical signs are less informative for diagnosing SCH in older adults compared to younger individuals.
• TSH measurements in elderly patients require cautious interpretation, especially when based on clinical signs.
• A reassessment of TSH reference ranges and improved monitoring strategies for thyroid dysfunction in the elderly are necessary.