Hypothyroidism%20(pediatric) Management
Follow Up
- Treatment adequacy is monitored by measuring serum free thyroxine (FT4) and thyroid-stimulating hormone (TSH) levels
- T4 dose adjusted by 25-50 mcg increments based on the serum TSH level measured 2-4 weeks after starting treatment and every 4-8 weeks thereafter until normal TSH is reached
- In children, serum TSH and FT4 levels should be assessed based on age-specific and method-specific reference ranges
- Once a target level of serum TSH is reached, measure TSH and FT4 levels every 2-3 months, provided that no other medications are taken that may change the bioavailability or absorption of the T4
- When patient has to switch to a different T4 brand, serum TSH must be checked 4-6 weeks later, then doses adjusted accordingly
- Intake of other medications that may alter T4 bioavailability warrants rechecking of serum TSH after 4-6 weeks and adjusting of T4 doses if needed
Considerations
Central hypothyroidism
- TSH is not used as a marker of adequate treatment
- Serum FT4 is a useful index
Congenital hypothyroidism
- Infants are monitored frequently in the first 2 years of life using serum TSH as primary parameter and FT4 as the secondary parameter, employing age-appropriate reference intervals
- During the 1st year of life, total T4 and FT4 is maintained in the upper half of the normal reference range
- Monitoring:
- Recheck T4, TSH
- 2-4 weeks after initial treatment has begun
- Every 1-2 months in first 12 months of life and those with moderate to severe hypothyroidism
- Every 1-3 months between 1-3 years of age
- Every 6-12 months from 3 years of age until end of growth
- For patients suspected of treatment noncompliance or with abnormal lab results, monitor more frequently
- Obtain FT4 and TSH measurements 4-6 weeks after T4 dose adjustments
- Blood samples for FT4 and TSH measurements should be collected ≥4 hours after T4 intake
- Recheck T4, TSH
- Several studies have suggested monthly monitoring for patients with the following:
- Dose adjustment within 1 month from prior visit
- Total T4/FT4 measurements within the lower half within 1 month from prior visit
- TSH of 5-10 mU/mL and total T4/FT4 measurements within the lower half within 1 month from prior visit
- TSH >10 mU/mL within 1 month from prior visit, even if total T4/FT4 levels are in the upper limit of normal
- TSH <0.1 mU/mL
- Assess permanence of congenital hypothyroidism
- If initial thyroid scan shows ectopic/absent gland, congenital hypothyroidism is permanent
- If initial TSH is <50 mU/L and no increase in TSH after newborn period, then trial off therapy at 3 years of age
- If TSH increases off therapy, consider permanent congenital hypothyroidism
- Should be performed in children >3 years
- If circulating T4 levels remain persistently low and TSH remains high despite progressively larger replacement doses of T4, it is important to determine the possibility of poor compliance
- The most frequent reason for failure to respond to replacement therapy has been interference with adsorption by soy-based formulas or with medications that contain iron
Thyroid Re-evaluation
- Thyroid axis re-evaluation should be done 4-6 weeks after temporary withdrawal of treatment in patients ≥3 years of age
- May be performed in patients <3 years with occasional increased TSH levels (eg positive TSH receptor antibodies, eutopic thyroid gland seen on imaging)
- Indicated for the following:
- If not done during infancy
- Child was born preterm or ill during initial evaluation and treatment
- Patients without known enzyme defects
- Normal goiter with or without goiter at initial evaluation
- Neonates with positive thyroid antibodies
- Patients without dosage increase/adjustments since start of treatment
- Should be deferred for those:
- With diagnosed thyroid ectopy, apparent athyreosis, or true athyreosis via imaging
- Diagnosed with dyshormonogenesis via genetic testing