Interpretation

Problem representation

Approach

1. History

• Poor height velocity or short stature
• Delayed puberty, fatigue, poor school performance, sleepiness
• Constipation, cold intolerance, dry skin, hair loss
• Weight gain out of proportion to height gain
• Neck swelling, dysphagia, voice change
• Family history of thyroid disease or autoimmune disease
• Type 1 diabetes, celiac disease, vitiligo
• Down syndrome, Turner syndrome, prior neck irradiation
• Drugs: valproate, lithium, amiodarone, iodine-containing medications/supplements
• Recent acute illness or recovery phase illness

2. Examination

• Plot height, weight, BMI, and height velocity on growth charts.
• Blood pressure and pulse.
• Pubertal assessment.
• Thyroid examination: diffuse goiter, firmness, asymmetry, nodules.
• Signs of hypothyroidism: dry/coarse skin, bradycardia, delayed reflex relaxation, periorbital puffiness.
• Look for other autoimmune features, such as vitiligo.

3. Investigations

1. Repeat serum TSH and free T4
   • Preferably in about 2 to 6 weeks if clinically well, or sooner if symptomatic.
   • An isolated TSH elevation should be confirmed before committing a child to lifelong therapy, unless free T4 is low or symptoms are convincing.
2. Anti-TPO antibody and anti-thyroglobulin antibody
   • Positive antibodies strongly support Hashimoto thyroiditis.
3. Thyroid ultrasound only if indicated
   • Goiter, asymmetry, palpable nodule, marked gland enlargement, or diagnostic uncertainty.
   • It is not routinely required for every elevated TSH.
4. Consider targeted tests according to history:
   • CBC, fasting lipid profile, liver enzymes if symptomatic or clearly hypothyroid.
   • Celiac screening if autoimmune thyroid disease is confirmed or symptoms/risk factors exist.
   • Review iodine exposure and medications.

Management

If free T4 is low

• Start levothyroxine under pediatrician or pediatric endocrinologist supervision.
• The child needs treatment, not observation alone.
• A 50 kg adolescent will often require a dose within an adolescent replacement range, but the exact initial dose must be chosen using free T4, severity, duration of disease, clinical status, and clinician assessment. Do not calculate or start the dose solely from this report.

If free T4 is normal and repeat TSH remains >10 mIU/L

• Refer to a pediatric endocrinologist.
• In pediatric practice, persistent TSH above 10 mIU/L, especially with thyroid antibodies, goiter, symptoms, impaired growth/puberty, or dyslipidemia, generally favors levothyroxine treatment rather than simple observation.
• Current evidence identifies TSH >10 mIU/L as a higher-risk threshold for underlying thyroid disease in children (review abstract).

If repeat TSH falls below 10 and free T4 is normal

• Observation may be reasonable.
• Repeat TSH and free T4 about every 6 months, with growth and puberty monitoring.
• Treat or refer earlier if TSH rises, free T4 falls, symptoms develop, growth decelerates, or goiter/antibodies are present.

Levothyroxine follow-up points

• Give once daily, ideally on an empty stomach, consistently.
• Keep iron, calcium, antacids, and soy-based supplements/foods separated from levothyroxine because they can reduce absorption.
• Recheck TSH and free T4 about 4 to 6 weeks after starting or changing dose.
• After stabilization, monitor approximately every 6 to 12 months during adolescence, with closer monitoring during periods of rapid growth.
• Do not use T3 preparations routinely for acquired pediatric hypothyroidism.

Bottom line