CORRELATION OF COGNITIVE TEST-SCORES AND ADEQUACY OF TREATMENT IN ADOLESCENTS WITH CONGENITAL HYPOTHYROIDISM

Purpose: To measure the frequency of noncompliance and its possible ef fect on school achievement test and cognitive test scores in our older patients with congenital hypothyroidism. Methods: Fifty patients born from 1976 through 1978 were studied at home when they were 14 years o f age. Each patient was given a battery of psychometric and school ach ievement tests, and blood for hormonal assays was drawn without forewa rning from 36 of the patients on the day of examination. Efforts were made to improve control after the second year. During the third summer the tests were repeated in 25 or the 29 patients who had been tested at the age of 14; thyrotropin and thyroxine concentrations were measur ed in 23 of these 25 patients. Results: At the age of 14 years 16 of t he 36 children had poorly controlled hypothyroidism, as defined by thy rotropin values greater than 15 mU/L. Of these 16 patients, 13 also ha d thyroxine concentrations of less than 85 nmol/L (6.6 mu g/dl). A sec ond examination at 15 or 16 years of age disclosed significant improve ments in hormonal concentrations without changes in thyroxine dosage. Poor control was demonstrated on at least one occasion in 74% of 27 ch ildren older than 12 years of age who had 3 to 8 thyrotropin measureme nts during a period of 9 months. Cognitive test results in the patient s did not differ from those in control subjects or from previous test results in the same children. The improved hormonal concentrations at the age of 15 or 16 years, however, were accompanied by significant im provement in cognitive test results; mean IQ increased from 106 to 112 (p = 0.002). Patients with greater improvement in hormonal values had significantly greater improvement in IQ. Conclusions: The prevalence of noncompliance in the adolescent children of our cohort with congeni tal hypothyroidism was high. Subsequent improvement in thyroid control was associated with significant improvement in psychometric test scor es.