Endogenous thyroid-stimulating hormone and radioactive iodine uptake in normal subjects

Area of Science:

• Endocrinology
• Gerontology
• Nuclear Medicine

Background:

• Thyroid function is regulated by the hypothalamic-pituitary-thyroid axis.
• Age-related changes in endocrine function are common but require further characterization.
• Thyroid-stimulating hormone (TSH) and radioactive iodine uptake (RAIU) are key indicators of thyroid function.

Purpose of the Study:

• To investigate the relationship between aging and thyroid function markers.
• To determine age-related trends in serum TSH and 24-hour RAIU.
• To assess the correlation of TSH and RAIU with the aging pituitary axis.

Main Methods:

• Serum TSH and 24-hour RAIU were measured in 105 healthy volunteers (52 male, 53 female; age range 20-68 years).
• Participants were stratified by age groups (20-29 years vs. 60-68 years) for comparative analysis.
• Statistical methods were employed to analyze age-related differences and correlations.

Main Results:

• Mean TSH levels were significantly higher in older adults (60-68 years) compared to younger adults (20-29 years) (1.59 ± 0.9 vs. 1.18 ± 0.5 microUI/mL, P = 0.037).
• Mean 24-hour RAIU was significantly lower in older adults compared to younger adults (14.92 ± 3.1% vs. 18.30 ± 4.5%, P = 0.009).
• TSH demonstrated a positive correlation, and 24-hour RAIU showed a negative correlation with advancing age.

Conclusions:

• Serum TSH levels increase, and 24-hour RAIU decreases with age in normal individuals.
• These findings suggest an age-related decline in pituitary axis function.
• The study highlights significant age-dependent alterations in thyroid function parameters.