Clinical Monitoring Guidelines for Congenital Hypothyroidism: Laboratory Outcome Data in the First Year of Life

ObjectiveTo examine whether current recommendations for thyroid status monitoring in children with congenital hypothyroidism (CH) (monthly in the first 6 months and every 3-4 months subsequently) are adequate, or whether monthly monitoring is necessary throughout the first year.Study designWe reviewed charts of 70 children with CH for initial thyroid-stimulating hormone (TSH), frequency of follow-up, dose changes, and thyroxine (T4) and TSH levels in the first year. Need for monthly monitoring was determined on the basis of guidelines to maintain T4/free T4 in the upper half of the normal range and rapidly normalize TSH.ResultsMonthly monitoring was justified in 75% in the first 6 months and 36% in the next 6 months. Children requiring monthly monitoring in the second 6 months had higher baseline TSH (P = .02) and lower T4 (P = .01) than those not requiring monthly monitoring. Thyroid dysgenesis, starting levothyroxine dose, sex, and ethnicity did not predict requirement for monthly monitoring. Thirty percent of children in the first and second 6 months had ≥1 high TSH level, with a T4/free T4 not in the upper half of the normal range.ConclusionMore than a third of children with CH require monthly monitoring between 6 to 12 months on the basis of study criteria. Current monitoring guidelines may need to be reexamined.