Unfavorable Course of Subclinical Hypothyroidism in Children with Hashimoto's Thyroiditis Compared to Those with Isolated Non-Autoimmune Hyperthyrotropinemia

Area of Science:

• Pediatric Endocrinology
• Thyroidology
• Autoimmune Diseases

Background:

• Subclinical hypothyroidism (SCH) is prevalent in children, with variable outcomes.
• The impact of Hashimoto's thyroiditis (HT) on SCH natural history in pediatric patients is unclear.
• Predictors for levothyroxine treatment initiation in pediatric SCH require further investigation.

Purpose of the Study:

• To determine if Hashimoto's thyroiditis (HT) negatively influences the natural course of subclinical hypothyroidism (SCH) in children.
• To identify predictors for levothyroxine medication in pediatric SCH patients.
• To compare the progression of SCH in patients with and without HT.

Main Methods:

• Retrospective review of medical records for 109 children (5-18 years) diagnosed with SCH between 2005 and 2014.
• Classification of patients into HT (n=37) and isolated non-autoimmune hyperthyrotropinemia (iso-NAHT, n=72) groups.
• Analysis of follow-up data (median 2 years) for levothyroxine initiation and antibody titers.

Main Results:

• Only 10.1% of pediatric SCH patients initiated levothyroxine during follow-up.
• Patients with HT had a significantly higher probability of requiring levothyroxine (21.6%) compared to iso-NAHT (4.2%).
• Underlying HT independently predicted thyroid function deterioration requiring medication (HR 4.6). High anti-thyroglobulin antibody (TGAbs) titers in the HT group strongly predicted later medication (HR 28.2).

Conclusions:

• Most pediatric SCH cases exhibit benign, self-resolving courses.
• Hashimoto's thyroiditis significantly increases the risk of progression to levothyroxine treatment in pediatric SCH.
• High anti-thyroglobulin antibody titers are a key predictor for medication need in pediatric SCH with HT.