Can long-term use of combination birth control (hormonal contraception) for over 10 years lead to hormonal imbalance and the development of a colloid nodule (thyroid nodule)?

From the Guidelines

There is no direct evidence to suggest that long-term use of combination birth control for over 10 years would cause a colloid nodule in the thyroid, as the relationship between hormonal contraceptives and thyroid nodule formation is not well-established. Colloid nodules are typically benign and are common in the general population, often associated with factors such as iodine deficiency, genetic predisposition, or occurring without a clear cause 1. While combination birth control can affect hormone levels, particularly estrogen and progesterone, it does not typically cause thyroid hormone levels to plummet or directly lead to thyroid nodule formation.

Some key points to consider:

• The use of combined hormonal contraceptives (CHCs) has been studied extensively for various conditions, but its direct link to thyroid nodule formation, specifically colloid nodules, is not clearly established in the provided evidence 1.
• CHCs are known to have various effects on the body, including changes in menstrual bleeding patterns, which are common among healthy women, and can sometimes be associated with conditions like endometriosis or benign ovarian tumors, but these are not directly related to thyroid health 1.
• It's essential to note that if a thyroid nodule is discovered, proper evaluation by a healthcare provider through blood tests to check thyroid function and possibly ultrasound or biopsy is necessary to determine if any treatment is needed.
• Post-birth control symptoms and thyroid issues can have overlapping features, making professional assessment crucial for proper diagnosis and management.

Given the information and the need to prioritize morbidity, mortality, and quality of life, it is recommended to focus on the evaluation and management of the thyroid nodule as per standard medical protocols, rather than attributing its cause directly to long-term combination birth control use. This approach ensures that any potential thyroid issues are addressed promptly and effectively, while also considering the broader context of the patient's health and well-being.

From the Research

Hormonal Contraception and Thyroid Function

• The use of hormonal contraception has been associated with a decreased incidence of hypothyroidism, as shown in a study published in 2024 2.
• However, another study published in 2021 found that a higher prevalence of hypothyroidism was found in women who had taken birth control pills, especially for more than 10 years 3.
• The effects of oral contraceptives on thyroid function are complex and involve the interaction of estrogen and progesterone with the hepatic production of thyroid-binding globulin (TBG) and the serum levels of thyroxine (T4) and triiodothyronine (T3) 4.

Colloid Nodules and Thyroid Function

• Thyroid nodules are common and can be detected in up to 65% of the general population, with most being benign and clinically insignificant 5.
• The diagnosis and management of thyroid nodules involve thyroid function testing and ultrasonographic characteristics, with suspicious sonographic patterns prompting cytological evaluation 5.
• There is no direct evidence to suggest that the use of combo birth control for over 10 years causes colloid nodules, but the potential impact of hormonal contraception on thyroid function may be a contributing factor 3, 4.

Potential Risks and Associations

• The use of hormonal contraception, especially for more than 10 years, has been associated with an increased risk of hypothyroidism 3.
• Estrogen-containing methods, such as combined oral contraceptive pills, may increase the risk of venous thrombosis 6.
• Subclinical hypothyroidism is known to be associated with a higher mean platelet volume than normal, which increases cardiovascular risk due to platelet hyperactivity caused by incomplete thrombocytopoietic maturation 4.