Serum TSH level stability after 5 years in euthyroid adults at low risk for thyroid dysfunction

Area of Science:

• Endocrinology
• Thyroid Function Testing
• Preventive Healthcare

Background:

• Thyroid dysfunction is common, necessitating monitoring strategies.
• Current guidelines suggest repeat thyroid stimulating hormone (TSH) testing at intervals.
• Assessing the optimal retesting interval for euthyroid adults is crucial for healthcare efficiency.

Purpose of the Study:

• To evaluate changes in thyroid function over 5 years in initially euthyroid adults.
• To determine the necessity of repeat TSH measurements in low-risk populations.
• To assess the cost-effectiveness of a 5-year thyroid function reevaluation interval.

Main Methods:

• 1,426 healthy adults with normal TSH were initially evaluated.
• Thyroid function was reassessed after 5 years in 1,215 participants.
• Thyroid stimulating hormone (TSH) levels were the primary measurement.

Main Results:

• Most participants remained euthyroid over the 5-year period.
• Few individuals developed abnormal TSH levels (>4 mIU/L or <0.4 mIU/L), often with prior borderline results.
• No significant differences were observed based on sex or age (≤60 vs >60 years).

Conclusions:

• Repeat TSH measurement every 5 years is not cost-effective for euthyroid adults without risk factors.
• Individuals with initial TSH between 0.6-3 mIU/L are unlikely to develop significant thyroid dysfunction within 5 years.
• Current screening intervals may be too frequent for low-risk populations.