Thyroid function during treatment with a new oral contraceptive combination containing desogestrel

Area of Science:

• Endocrinology
• Pharmacology

Background:

• Oral contraceptives are widely used by women of reproductive age.
• Understanding their impact on endocrine function, including thyroid regulation, is crucial for patient health.
• Desogestrel and ethinyloestradiol are common components of combined oral contraceptives.

Purpose of the Study:

• To evaluate the effects of a combined oral contraceptive containing desogestrel and ethinyloestradiol on thyroid function in healthy women.
• To assess changes in key thyroid hormone levels and pituitary response during and after treatment.

Main Methods:

• A study involving 15 healthy female volunteers over three 28-day cycles (21 days of treatment, 7 days off).
• Serum levels of thyroxine, free thyroxine index, thyroxine-binding globulin, triiodothyronine uptake, and thyrotropin (TSH) were measured.
• Free thyroxine concentration and pituitary response to TSH-releasing hormone (TRH) were also assessed.

Main Results:

• Significant increases in serum thyroxine, free thyroxine index, and thyroxine-binding globulin were observed during treatment.
• A decrease in thyroxine/thyroxine-binding globulin ratio and triiodothyronine uptake was noted.
• Serum triiodothyronine and TSH concentrations remained unchanged, as did the pituitary response to TRH.
• All measured parameters returned to baseline levels after treatment cessation.

Conclusions:

• The oral contraceptive combination of desogestrel and ethinyloestradiol did not significantly alter overall thyroid function in healthy women.
• Observed changes in binding proteins and related indices were within normal physiological limits and did not indicate thyroid dysfunction.
• The pituitary-thyroid axis remained functional during and after oral contraceptive use.