Jacoba J Bongers-Schokking1, Wilma C M Resing2, Wilma Oostdijk3, Yolanda B de Rijke4,5, Sabine M P F de Muinck Keizer-Schrama1. 1. Department of Pediatrics, Sophia Children's Hospital Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands. 2. Department of Developmental and Educational Psychology, Faculty of Social Sciences, University of Leiden, Leiden, the Netherlands. 3. Department of Pediatrics, Leiden University Medical Center, Leiden, the Netherlands. 4. Department of Clinical Chemistry, Division of Endocrinology, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands. 5. Department of Internal Medicine, Division of Endocrinology, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands.
Abstract
BACKGROUND: In congenital hypothyroidism (CH), age-specific reference ranges (asRR) for fT4 and thyrotropine (TSH) are usually used to signal over/under-treatment. We compared the consequences of individual fT4 steady-state concentrations (SSC's) and asRR regarding over-treatment signaling and intelligence quotient at 11 y (IQ11) and the effect of early over-treatment with high L-T4 dosages on IQ11. METHODS: Sixty-one patients (27 severe, 34 mild CH) were psychologically tested at 1.8, 6, and 11 y. Development scores were related to over-treatment in the period 0-24 mo, relative to either individual fT4SSC's or asRR. Three groups were formed, based on severity of over/under-treatment 0-5 mo (severe, mild, and no over/under-treatment). RESULTS: FT4 and TSH asRR missed 41-50% of the over-treatment episodes and consequently 22% of the over-treated patients, classified as such by fT4SSC's. Severe over-treatment 0-5 mo led to lowered IQ11's and to a 5.5-fold higher risk of IQ11 < 85 than other treatment regimes. Under-treatment had no effect on development scores. Initial L-T4 dosages >10 µg/kg resulted in a 3.7-fold higher risk of over-treatment than lower dosages. CONCLUSIONS: Data suggest that asRR, compared to fT4SSC's, signal over-treatment insufficiently. Using fT4SSC's and avoiding over-treatment may optimize cognitive outcome. Lowered IQ11's are usually a late complication of severe early over-treatment.
BACKGROUND: In congenital hypothyroidism (CH), age-specific reference ranges (asRR) for fT4 and thyrotropine (TSH) are usually used to signal over/under-treatment. We compared the consequences of individual fT4 steady-state concentrations (SSC's) and asRR regarding over-treatment signaling and intelligence quotient at 11 y (IQ11) and the effect of early over-treatment with high L-T4 dosages on IQ11. METHODS: Sixty-one patients (27 severe, 34 mild CH) were psychologically tested at 1.8, 6, and 11 y. Development scores were related to over-treatment in the period 0-24 mo, relative to either individual fT4SSC's or asRR. Three groups were formed, based on severity of over/under-treatment 0-5 mo (severe, mild, and no over/under-treatment). RESULTS: FT4 and TSH asRR missed 41-50% of the over-treatment episodes and consequently 22% of the over-treated patients, classified as such by fT4SSC's. Severe over-treatment 0-5 mo led to lowered IQ11's and to a 5.5-fold higher risk of IQ11 < 85 than other treatment regimes. Under-treatment had no effect on development scores. Initial L-T4 dosages >10 µg/kg resulted in a 3.7-fold higher risk of over-treatment than lower dosages. CONCLUSIONS: Data suggest that asRR, compared to fT4SSC's, signal over-treatment insufficiently. Using fT4SSC's and avoiding over-treatment may optimize cognitive outcome. Lowered IQ11's are usually a late complication of severe early over-treatment.
Authors: Jacoba J Bongers-Schokking; Maria A J de Ridder; Yolanda B de Rijke; Sabine M P F de Muinck Keizer-Schrama Journal: Thyroid Date: 2013-02 Impact factor: 6.568