Hashimoto's Thyroiditis in Children: Medication Titration and Real-World Monitoring
Initial Assessment and Treatment Decision
Most children with Hashimoto's thyroiditis who are euthyroid at presentation do not require immediate levothyroxine treatment, but those with subclinical or overt hypothyroidism, goiter, symptoms, or associated conditions (Turner syndrome, Down syndrome, other autoimmune diseases) should be started on therapy. 1
When to Start Treatment
- Overt hypothyroidism: Start levothyroxine immediately when TSH is elevated with low free T4 2, 3
- Subclinical hypothyroidism with progression: Treat if TSH is persistently elevated (especially >10 mIU/L) with progressive deterioration, goiter, or symptoms 1
- Euthyroid with high-risk features: Consider treatment for children with goiter, hypothyroid symptoms, or comorbid conditions like Turner/Down syndrome 1
- Euthyroid without complications: Monitor without treatment; most remain euthyroid long-term 3
Starting Dose
The initial levothyroxine dose for pediatric hypothyroidism is 1.6 mcg/kg/day given as a single morning dose. 2
- For infants 0-3 months at risk for cardiac failure, start at a lower dose and increase every 4-6 weeks 2
- For children at risk for hyperactivity, start at one-fourth the full replacement dose and increase weekly by one-fourth increments 2
- The typical starting dose in clinical practice ranges from 1.6-1.78 mcg/kg/day 4, 5
Monitoring Schedule
Initial Phase (First 6 Months)
Check TSH and free T4 at 2 weeks and 4 weeks after starting treatment, then 2 weeks after any dose change. 2
- Failure of T4 to increase into the upper half of normal range within 2 weeks, or TSH to decrease below 20 mIU/L within 4 weeks, indicates inadequate therapy 2
- Before increasing the dose, assess compliance, actual dose administered, and method of administration 2
Maintenance Phase
Once thyroid function stabilizes, monitor TSH and free T4 every 3-12 months until growth is completed. 2
- After achieving stable thyroid function for 2 years in untreated patients with mild TSH elevation, monitoring intervals can be extended 1
- For treated patients on stable doses, evaluate every 6-12 months and whenever clinical status changes 2
- Poor compliance or abnormal values necessitate more frequent monitoring 2
Clinical Monitoring
Perform routine clinical examination at regular intervals, including assessment of growth velocity, development, mental and physical growth, and bone maturation. 2
- Monitor for symptoms of over-treatment (hyperactivity, tachycardia, weight loss) or under-treatment (fatigue, constipation, poor growth) 2
- Track height and weight at each visit; hypothyroidism can affect linear growth 2
- Assess for goiter size changes; levothyroxine can reduce thyroid volume in treated children 4
Dose Titration Strategy
Target Goals
The primary goal is to normalize serum TSH levels, though TSH may not fully normalize in some patients with in utero hypothyroidism due to pituitary-thyroid feedback resetting. 2
- Maintain free T4 in the upper half of the normal range 2
- In children with congenital hypothyroidism, some TSH elevation may persist despite adequate T4 levels 2
Dose Adjustments
Adjust levothyroxine dose based on TSH and free T4 results, waiting 6-8 weeks between changes to allow steady-state levels. 2
- Increase dose if TSH remains elevated or free T4 is in lower half of normal range 2
- Decrease dose if TSH is suppressed or patient shows signs of hyperthyroidism 2
- For significantly overweight children, base dosing on ideal body weight to avoid excessive steroid exposure 6
Special Considerations in Real-World Practice
Antibody Monitoring
Thyroid antibody levels (TPO and thyroglobulin antibodies) tend to decrease with levothyroxine treatment, though this is not a primary treatment target. 3
- Antibody titers decreased significantly in subclinical hypothyroid patients treated with levothyroxine 3
- Thyroglobulin antibodies decreased in overt hypothyroid patients, though TPO antibodies showed less consistent change 3
Thyroid Ultrasound
Thyroid ultrasound can be useful for monitoring disease progression and may help guide therapeutic decisions, particularly when considering dose reduction or discontinuation. 7
- Levothyroxine treatment can decrease thyroid volume in euthyroid children with Hashimoto's, though the effect is time-limited 4
- Serial ultrasound changes may parallel thyroid function changes and indicate remission 7
- Mean thyroid volume decreased by -1.01 SDS over 30 months in treated children versus +0.27 SDS increase in untreated children 4
Potential for Remission
Hashimoto's thyroiditis can go into remission in some children, making periodic reassessment of treatment necessity important. 7
- Consider trial off medication in patients with normalized ultrasound findings and stable thyroid function on low-dose levothyroxine 7
- After stopping treatment, monitor free T4 and TSH at 8,17, and 30 weeks to assess for recurrence 7
- Most children who are euthyroid at presentation remain euthyroid during follow-up 3
Common Pitfalls to Avoid
Overtreatment Risks
Levothyroxine has a narrow therapeutic index; overtreatment in pediatric patients can cause craniosynostosis, accelerated bone age, and adverse effects on growth and development. 2
- Excessive doses may impair linear growth despite normalizing TSH 2
- Monitor for signs of hyperthyroidism including tachycardia, weight loss, and behavioral changes 2
Undertreatment Risks
Inadequate treatment may adversely affect cognitive development and linear growth in children with congenital and acquired hypothyroidism. 2
- Persistent elevation of TSH despite apparent adequate dosing may indicate poor absorption, non-compliance, or drug interactions 2
- Assess compliance before assuming treatment failure 2
Premature Treatment Discontinuation
Do not stop treatment in children with overt hypothyroidism without clear evidence of remission on ultrasound and sustained normal thyroid function. 7