The TRH stimulation test in endemic goitre in Greece

Area of Science:

• Endocrinology
• Thyroid Research
• Public Health

Background:

• Iodine deficiency is a significant global health concern affecting thyroid function.
• The relationship between iodine intake, thyroid hormone levels, and goiter development requires further elucidation.
• Understanding compensatory mechanisms in mild iodine deficiency is crucial for public health strategies.

Purpose of the Study:

• To investigate thyroid hormone profiles (serum T4, RT3U, TSH) in individuals from an iodine-deficient region.
• To compare thyroid function parameters between goitrous and nongoitrous individuals in an iodine-deficient area.
• To assess the impact of thyrotropin-releasing hormone (TRH) stimulation on TSH levels in this population.

Main Methods:

• Serum T4, RT3U, and TSH were measured in 30 subjects from an iodine-deficient area in Greece.
• Subjects were divided into goitrous (n=16) and nongoitrous (n=14) groups.
• Measurements were taken before and 30 minutes after TRH injection, with comparisons to 14 control subjects from a non-endemic area.

Main Results:

• In the iodine-deficient area, serum T4 was decreased, while RT3U and TSH levels were normal.
• TSH levels remained normal both before and after TRH stimulation in the iodine-deficient subjects.
• A negative correlation between serum T4 and TSH was observed in the goitrous group.

Conclusions:

• Mild iodine deficiency in this region primarily affects serum T4 levels, with normal RT3U and TSH responses.
• The mechanisms by which nongoitrous individuals in iodine-deficient areas maintain normal thyroid function without goiter remain unclear.
• Goiter development in iodine deficiency may represent a maladaptive response rather than a purely compensatory process.