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Effects of hyperthyroidism on binding proteins for steroid hormones
P Caron1, A Bennet, C Barousse
1Service d'Endocrinologie CHU Purpan, Toulouse, France.
Clinical Endocrinology
|August 1, 1989
Summary
Thyroid hormone triiodothyronine (T3) alters sex hormone binding globulin (SHBG) and corticosteroid binding globulin (CBG) levels. SHBG capacity increases while CBG capacity decreases, suggesting their ratio may indicate thyroid hormone action.
Area of Science:
- Endocrinology
- Hormone Regulation
- Thyroid Function
Background:
- Sex hormone binding globulin (SHBG) and corticosteroid binding globulin (CBG) are key transport proteins for steroid hormones.
- Thyroid hormones, particularly triiodothyronine (T3), are known to influence various metabolic processes and protein synthesis.
Purpose of the Study:
- To investigate the impact of L-triiodothyronine (T3) therapy and hyperthyroidism on SHBG and CBG binding capacities.
- To determine if the ratio of SHBG to CBG binding capacities correlates with thyroid hormone levels and can serve as a biochemical marker.
Main Methods:
- Weekly measurement of SHBG and CBG binding capacities in women undergoing T3 therapy.
- Measurement of SHBG and CBG binding capacities in hyperthyroid subjects before and after antithyroid drug treatment.
- Statistical analysis to correlate the SHBG/CBG ratio with triiodothyronine levels.
Main Results:
- T3 therapy led to increased SHBG binding capacity and decreased CBG binding capacity.
- Hyperthyroid subjects exhibited higher SHBG and lower CBG binding capacities compared to euthyroid individuals.
- A significant positive correlation was found between the ratio of SHBG to CBG binding capacities and T3 levels (P < 0.01).
Conclusions:
- Thyroid hormone status significantly influences the binding capacities of SHBG and CBG in opposite directions.
- The ratio of SHBG to CBG binding capacities shows potential as a sensitive biochemical index for assessing peripheral thyroid hormone action.