Thyroid Autoimmunity and Subclinical Hypothyroidism in Prolactinoma: A Case Control Study

Area of Science:

• Endocrinology
• Thyroidology
• Reproductive Endocrinology

Background:

• Hyperprolactinemia, often caused by prolactinoma, is a common endocrine disorder.
• Thyroid dysfunction, including autoimmunity and hypothyroidism, can coexist with hyperprolactinemia.
• The relationship between prolactinoma and thyroid autoimmunity requires further investigation.

Purpose of the Study:

• To compare the prevalence of thyroid autoimmunity and subclinical hypothyroidism in patients with hyperprolactinemia due to prolactinoma versus healthy controls.
• To assess the progression of thyroid autoimmunity to subclinical hypothyroidism in patients with hyperprolactinemia.

Main Methods:

• A cross-sectional study involving 78 treatment-naive prolactinoma patients and 92 healthy controls.
• Measurement of serum prolactin (PRL), thyroid-stimulating hormone (TSH), total thyroxine (T4), anti-thyroid peroxidase (anti-TPO), and anti-thyroglobulin (anti-Tg) antibodies.
• Comparison of thyroid autoimmunity and subclinical hypothyroidism rates between the groups.

Main Results:

• No significant difference in T4 or TSH levels between prolactinoma patients and controls.
• Similar prevalence of anti-thyroid antibodies in both groups (25% in patients vs. 20% in controls, P=0.56).
• Subclinical hypothyroidism was more common in antibody-positive hyperprolactinemia subjects compared to antibody-positive controls.

Conclusions:

• Untreated prolactinoma is not associated with an increased prevalence of thyroid autoimmunity compared to healthy individuals.
• Subclinical hypothyroidism is more prevalent in patients with hyperprolactinemia who also have thyroid antibodies.
• These findings suggest a potential interaction between thyroid autoimmunity and hyperprolactinemia in the development of subclinical hypothyroidism.