Treatment

The main goal of treatment is to achieve growth and mental development that is as close as possible to a child’s genetic potential (1).

Treatment of all hypothyroid neonates should be started as soon as possible – within the first 18 days of life (2).

• main aim of treatment is to increase the serum free T4 levels to the normal range as rapidly as possible (2)
• failure to normalize serum T4 over one week may result in lower intelligence scores (1)

Treatment is by replacement with thyroxine

• the American Academy of Paediatrics (AAP) and the European Society for Paediatric Endocrinology (ESPE) recommends initial levothyroxine dose of 10-15 micrograms/kg per day (1)
• dose should be adjusted according to the growth to keep serum FT4 in the upper half of the reference range and the TSH levels normal (2)

The risk of overtreatment is advancement of bone age and subsequent reduced adult height; monitoring is therefore with growth measurement, bone age assessment and levels of free T4 and TSH.

With a stable clinical scenario children might require monitoring

• every 1-2 months in the first year of life
• 3-6 monthly thereafter until growth is completed (2)

Re evaluation of all infants with repeat estimation of TSH and FT4 should be done at 3 years with a period of at least 2 weeks off thyroxine replacement therapy prior to the test in order to exclude the possibility of a transient effect of maternal antibodies (2)

With such an apparently well child it is sometimes difficult for parents to remember to give thyroxine daily, but their memory may improve near to a clinic visit, reflected by a normal T4 but a high TSH; the latter reflects a longer time period since it takes a longer time to correct.

Reference:

• (1) Rastogi MV, LaFranchi SH. Congenital hypothyroidism. Orphanet J Rare Dis. 2010;5:17
• (2) Association for Clinical Biochemistry (ACB), British Thyroid Association (BTA), British Thyroid Foundation (BTF) 2006.UK guidelines for the use of thyroid function tests