Aspects of thyroid function during use of Norplant implants

Area of Science:

• Endocrinology
• Reproductive Health
• Thyroid Function

Background:

• Contraceptive implants are widely used for birth control.
• Understanding the impact of hormonal contraceptives on thyroid function is crucial for patient health.
• Norplant and Norplant-2 are progestin-only contraceptive implants.

Purpose of the Study:

• To investigate the effects of Norplant and Norplant-2 implants on thyroid hormone levels.
• To assess changes in thyroid stimulating hormone (TSH) and thyroid hormone concentrations.
• To determine if Norplant use alters thyroid function in women.

Main Methods:

• Blood samples were collected from 18 women using Norplant or Norplant-2 implants for six months.
• Plasma levels of thyroxin (T4), triiodothyronine (T3), T3-uptake, and TSH were measured.
• Free T4-index and free T3-index were calculated to assess thyroid hormone availability.

Main Results:

• A decrease in total thyroxin (T4) and an increase in T3-uptake were observed.
• These changes suggest a reduction in thyroid binding proteins during Norplant treatment.
• Free T4-index, free T3-index, and TSH levels remained unchanged, indicating unaltered thyroid hormone status.

Conclusions:

• Norplant and Norplant-2 contraceptive implants do not significantly affect thyroid function.
• Thyroid hormone levels and TSH remain stable in women using these implants.
• These findings support the safety of Norplant implants regarding thyroid health.