Background: An early diagnosis and treatment based on neonatal screening offers a normal cognitive development in patients affected with congenital hypothyroidism (CH). However, several studies within cohorts of young adults have shown a still existing difference compared to control groups of up to eight IQ points. Moreover it has been claimed recently that a high L-T4 dose with subsequent episodes of overtreatment results in less favourable IQ outcomes (Bongers-Shokking, J Clin Endocrinol Metab, 2013).
Objective and hypotheses: We tested the cognitive outcome in the cohort of CH patients diagnosed in the Berlin screening program born from 1979 to 2003 who were treated early and with a high L-T4 dose.
Method: We recruited 74 patients, nine were not euthyroid and two had conductive hearing problems who were excluded and 36 control siblings. We performed a variety of cognitive tests. Episodes of over- and undertreatment were calculated based on the individual TSH ssc (steady state concentration) (Bongers-Shokking, J Clin Endocrinol Metab, 2013).
Results: Mean initial L-T4-dose was 12.8 μg/kg at mean age of 9 days; TSH normalization at median treatment-time of 13.5 days. We did not find a significant difference of global IQ in CH patients compared to their sibling control group (102.98 vs 99.19). We did not find a correlation of the number of suppressed TSH ssc with IQ.
Conclusion: Early treatment of CH patients with a high dose of 12.8 μg/kg that normalize TSH within 14 days lead to a normal IQ without difference to sibling controls although such treatment is associated with episodes of suppressed TSH.
20 - 22 Sep 2014
European Society for Paediatric Endocrinology