A strategy to avoid missed cases in a Brazilian neonatal TSH screening program for congenital hypothyroidism.

BACKGROUND: There have been reports of patients with primary hypothyroidism not identified by TSH measurement due to a presumably delayed rise in serum TSH. However, there are no data on the incidence of false negative results in neonatal screening programs employing primary TSH assay for diagnosis. AIM: To investigate the incidence of false negative results in a neonatal screening program using the primary TSH approach and evaluate a strategy to avoid misdiagnosis. INFANTS AND METHODS: 190 newborns, with initial TSH > 15.0 IU/l and < 20.0 IU/l (screening cutoff). These infants were submitted to a second TSH measurement around 30 days after the first screening. RESULTS: Thirty days after the first screening, four of the 190 infants (2.1%) remained with TSH levels around the cut-off screening level or higher. Of these four patients, three had an absence of thyroid gland on ultrasonography, with a final diagnosis of dysgenesis. The fourth patient had a normal shaped gland in its usual location by ultrasonography, with an outcome of transitory congenital hypothyroidism. CONCLUSIONS: The incidence of missed congenital hypothyroidism diagnoses in this neonatal screening program based on the TSH approach was low and acceptable. Nevertheless, with the proposed strategy, the risk of false negative results can be reduced without significant impact on the overall cost of the screening program.

High prevalence of extrathyroid malformations in a cohort of Brazilian patients with permanent primary congenital hypothyroidism.

The objective of this study was to evaluate the prevalence of major congenital malformations in a cohort of children with permanent primary congenital hypothyroidism (PCH). This cross-sectional study was conducted in 76 consecutive, unselected children with PCH recruited from a district hospital outpatient clinic. Malformations were identified by clinical examination. The prevalence of major congenital malformations in these patients was compared with the prevalence of malformations in children born at Hospital de Clínicas de Porto Alegre (HCPA). The etiology of hypothyroidism was established by scintigraphy and ultrasonography. Hypothyroidism was caused by thyroid dysgenesis in 67 patients (one case of hemiagenesis, 24 of ectopia, and 42 of agenesis); the gland was normally located and shaped in nine patients. Ten patients (13.2%) had major congenital malformations (1,316/10,000 patients), mostly cardiac. Malformations were observed only in patients with dysgenesis: thyroid agenesis (n = 7) and sub-lingual ectopic thyroid (n = 3). The prevalence of malformations was significantly higher (RR = 2.6; CI 95%: 1.3-4.8; p = 0.005) in this group than in HCPA newborns (509/10,000 patients). In conclusion, a high rate of extrathyroid congenital malformations, mostly cardiac, was found for patients with permanent PCH, especially thyroid dysgenesis. The present data support the existence of an association between CH and increased prevalence of congenital malformations.

Accuracy of ultrasonography to establish the diagnosis and aetiology of permanent primary congenital hypothyroidism.

OBJECTIVE: To compare ultrasonography and 99mTc thyroid scintigraphy for the aetiologic diagnosis of permanent congenital hypothyroidism (CH). STUDY DESIGN: Eighty-eight consecutive patients with CH were recruited at an endocrinology outpatient clinic and submitted to high-frequency ultrasonography and to 99mTc scintigraphy. RESULTS: Seventy-six patients were diagnosed with permanent CH and 12 with transitory CH. The agreement between ultrasound and scintigraphy was very high (kappa coefficient = 0.866; P < 0.001) for the entire group. In permanent CH patients, ultrasonography identified 67 cases of dysgenesis (absence of thyroid gland in the usual anatomical location in 66 and hemiagenesis in one), and this diagnosis was confirmed by scintigraphy (absence of functional thyroid tissue in 43 and ectopia in 24). In the other nine permanent CH patients, the thyroid was in the usual anatomical location on ultrasonography but scintigraphy did not identify functional tissue in one patient. In the 12 transitory CH patients, a normally shaped thyroid was detected by ultrasound in the usual location, whereas scintigraphy showed absence of functional tissue in two identical twins and scarce concentration of isotope in a third patient. CONCLUSION: Ultrasonography is an accurate method to establish the presence of dysgenesis and might be used as the first imaging tool in patients with CH, whereas scintigraphy should be used mainly to distinguish agenesis from ectopia. Further examination is required to differentiate permanent CH with a normally located and shaped gland from transitory hypothyroidism.

Predictors of intellectual outcome in a cohort of Brazilian children with congenital hypothyroidism.

OBJECTIVE: To identify predictors of intellectual development in a cohort of children with permanent primary congenital hypothyroidism. DESIGN: Cohort study with intellectual development as the outcome. PATIENTS AND MEASUREMENTS: Thirty-one consecutive newborns with permanent primary congenital hypothyroidism diagnosed by a screening programme were recruited from the outpatient clinic of a district hospital and underwent psychometric evaluation with the Wechsler Intelligence Scales after a minimum follow-up of 4 years. RESULTS: Eight of the 31 patients (25.8%) presented impaired intellectual development (full-scale intellectual quotient < 85), and one of them presented mental deficiency (full-scale intellectual quotient