Serum reverse-T3 determinations in the laboratory diagnosis of hyperthyroidism

Area of Science:

• Endocrinology
• Clinical Chemistry
• Thyroidology

Background:

• Hyperthyroidism diagnosis relies on accurate thyroid hormone level assessment.
• The utility of reverse-T3 (rT3) in diagnosing hyperthyroidism alongside T3 and T4 requires further clarification.
• Binding proteins can influence total serum thyroid hormone measurements.

Purpose of the Study:

• To evaluate the diagnostic accuracy of serum reverse-T3 levels in hyperthyroidism.
• To compare the discriminatory value of serum T3, T4, and rT3 in patients with suspected hyperthyroidism.
• To assess the impact of binding protein correction on these hormone measurements.

Main Methods:

• Investigated 47 patients with clinical signs of hyperthyroidism.
• Measured total serum T3, T4, and reverse-T3 levels.
• Compared results with thyroid function tests and corrected for binding proteins.

Main Results:

• Total serum T3 levels demonstrated superior diagnostic value compared to T4 and rT3.
• This superiority was maintained even after correcting for binding proteins.
• Serum T3 estimation proved more effective than T4 and rT3 in differentiating hyperthyroidism.

Conclusions:

• Total serum T3 is a more reliable indicator for diagnosing hyperthyroidism than T4 or rT3.
• Reverse-T3 estimation offers limited additional diagnostic value for hyperthyroidism in this context.
• Accurate diagnosis of hyperthyroidism is best achieved through total serum T3 level determination.