Conventional and dual competitive binding analyses of thyroxine using the Thyopac-4 kit

Area of Science:

• Endocrinology
• Clinical Chemistry
• Diagnostic Assays

Background:

• Accurate assessment of thyroid function is crucial for diagnosing and managing thyroid disorders.
• Thyroid hormone levels, particularly thyroxine (T4), are influenced by binding proteins like thyroxine-binding globulin (TBG).
• Existing methods may require multiple kits or complex procedures for simultaneous T4 and ETR determination.

Purpose of the Study:

• To describe a simplified method for simultaneous determination of thyroxine (T4) and the effective thyroxine ratio (ETR).
• To evaluate the utility of the Thyopac-4 kit for assessing thyroid status in various physiological and pathological conditions.
• To assess the method's reliability in differentiating normal from abnormal thyroid states, independent of TBG variations.

Main Methods:

• Utilized the Thyopac-4 kit for simultaneous measurement of T4 and ETR.
• Collected ETR values from normal subjects, hyperthyroid patients, hypothyroid patients, and pregnant women.
• Assessed ETR and T4 values in cases of TBG deficiency and nephrotic syndrome.
• Correlated ETR values with free thyroxine index (FTI) using regression analysis.

Main Results:

• Thyopac ETR values were distinct for normal (1.00 ± 0.03), hyperthyroid (1.22 ± 0.11), and hypothyroid (0.87 ± 0.04) individuals.
• Pregnant women showed a mean ETR of 1.02 ± 0.05.
• Cases with TBG deficiency and nephrotic syndrome exhibited normal ETR values.
• A significant correlation (γ = +0.961) was found between ETR (x) and FTI (y), described by the equation y = 71.7x² - 88.4x + 24.2.

Conclusions:

• The Thyopac-4 method provides a simple and effective means for simultaneous T4 and ETR determination.
• Thyopac ETR is a reliable indicator for differentiating thyroid function status, irrespective of TBG level fluctuations.
• Simultaneous T4 measurement aids in detecting alterations in TBG levels through inconsistent ETR values.