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Persistent infantile hypothyroidism attributable to thyroxine-binding globulin deficiency
1University of Wisconsin Children's Hospital, 600 Highland, Avenue, Madison, WI 53792, USA. alcarrel@facstaff.wisc.edu
Insights
Thyroid-binding globulin (TBG) deficiency can cause hypothyroidism, as seen in a unique infant case. Hormone replacement therapy normalized thyroid levels, highlighting the importance of monitoring TBG deficiency.
Area of Science:
- Endocrinology
- Pediatrics
- Genetics
Background:
- Newborn screening is crucial for identifying congenital disorders.
- Thyroid-binding globulin (TBG) deficiency is a rare genetic condition affecting thyroid hormone transport.
- Congenital hypothyroidism necessitates timely diagnosis and management to prevent developmental issues.
Observation:
- An infant presented with elevated thyroid-stimulating hormone (TSH) and low free thyroxine (fT4) post-newborn screening.
- This indicated persistent congenital hypothyroidism.
- The infant was diagnosed with thyroid-binding globulin (TBG) deficiency.
Findings:
- Thyroxine (T4) supplementation normalized fT4 and TSH levels in the first five years.
- Discontinuation of T4 therapy led to recurrent hyperthyrotropinemic hypothyroidism.
- This case is the first reported instance of hypothyroidism directly linked to TBG deficiency.
Implications:
- TBG deficiency, though rare, can manifest as hypothyroidism requiring lifelong hormone management.
- This case underscores the need for careful monitoring in individuals with TBG deficiency.
- Early diagnosis and intervention are vital for managing thyroid disorders in infants.
Abstract:
An infant diagnosed with thyroid-binding globulin (TBG) deficiency after newborn screening demonstrated persistent elevation of thyroid-stimulating hormone (TSH) and abnormally low free thyroxine (fT4) levels. Treatment with thyroxine (T4) normalized fT4 and TSH levels during the first 5 years of life, but withdrawal of T4 supplementation at that time was associated with return of hyperthyrotropinemic hypothyroidism. To our knowledge, this patient is the first reported case of TBG deficiency-associated hypothyroidism. In rare instances, TBG deficiency may lead to hypothyroidism requiring hormone supplementation.