Altered Thyroid Feedback Loop in Klinefelter Syndrome: From Infancy Through the Transition to Adulthood
Authors' conclusion
From infancy through adulthood, KS is characterized by increased morphofunctional abnormalities of the thyroid gland, combined with a central feedback dysregulation sustained by the effect of hypogonadism on D2 deiodinase.
Study context
- Population
- Patients with Klinefelter syndrome across the life span (25.9 ± 16.1 years)patients with Klinefelter syndrome (KS)
- Participants
- 254 patients
- Exposure
- KS vs non-KS age-matched controls
- KSn = 254
- Outcome
- HPT axis and thyroid ultrasonographic (US) appearance
Methodological detailsage-matched non-KS controls, in vitro pituitary D2 testing
- Age-matched non-KS controls
- In vitro pituitary D2 testing
Main finding
As reported in the abstract
- Thyroid autoimmunity more prevalent in KS at all ages; Antibody (Ab)-negative vs Ab-positive cohorts not different
- Signs of thyroid dysfunction (reduced volume, lower echogenicity, increased inhomogeneity) more prominent in KS than euthyroid controls
- Free thyroid hormones lower in prepubertal, pubertal and adult KS; TSH lower only in adults
- Peripheral sensitivity to thyroid hormones unaltered in KS, suggesting a dysfunctional hypothalamic-pituitary-thyroid (HPT) axis
- Testosterone the only factor associated with thyroid function and appearance
Observational data: associations, not effects.
Further findings
In vitro pituitary D2 expression and activity
- Inhibitory effect of testosterone on pituitary D2 expression and activity
Original publication
Altered Thyroid Feedback Loop in Klinefelter Syndrome: From Infancy Through the Transition to Adulthood. J Clin Endocrinol Metab. Published 22 May 2023. doi:10.
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