Sonographic assessment of congenitally hypothyroid children in Iran.

INTRODUCTION: Considering the high prevalence of congenital hypothyroidism (CH) in Isfahan, it seems that it is necessary to investigate the aetiology of the disorder and its related factors. The aim of this study was to determine the aetiology of CH among children in Isfahan province. MATERIAL AND METHODS: In this cross-sectional study, the aetiology of CH and the volume of the thyroid was assessed using neck ultrasonography. The results of thyroid function screening tests were additionally recorded. The correlation between ultrasonographic findings and the level of TSH and as well as T4 was determined. RESULTS: During this study 385 CH patients aged 0-3 years were studied. According to ultrasonographic findings, in 19.9% of patients the aetiology of CH was dysgenesis (agenesis, ectopy, and hemiagenesis) and 80.1% had normal thyroid. Mean thyroid gland volume in all studied patients was 0.78 ± 0.44 mL. The prevalence of ultrasonographic findings was as follows: normal 80.1%, agenesis 12.7%, hemiagenesis 5.8%, and ectopy 1.4%. There was a significant correlation between thyroid volume and TSH and T4 and as well as between TSH and ultrasonographic findings (p 〈 0.05). CONCLUSIONS: In spite of the limitations of ultrasonography in the field of determining the aetiology of CH, it is an appropriate imaging tool for determining the volume of the thyroid gland in children. Considering that the rate of goitrous gland was low, it seems that iodine deficiency could not be responsible for the high rate of CH in this region.

Role of corticotropin-releasing hormone testing in assessment of hypothalamic-pituitary-adrenal axis function in infants with congenital central hypothyroidism.

CONTEXT: The Dutch neonatal congenital hypothyroidism (CH) screening program detects infants with CH of central origin (CH-C). These infants have a high likelihood of multiple pituitary hormone deficiencies. ACTH deficiency especially poses an additional risk for brain damage and may be fatal. OBJECTIVE: Our objective was to evaluate different tools for assessment of the integrity of the hypothalamus-pituitary-adrenocortex (HPA) axis in young infants, aiming for a strategy for reliable and timely diagnosis. DESIGN, SETTING: This is a Dutch nationwide prospective study (enrollment 1994-1996). Patients were included if neonatal CH screening results were indicative of CH-C and HPA axis function could be tested within 6 months of birth. PATIENTS: Nine male and three female infants with CH-C and four infants with false-positive screening results or transient hypothyroidism were included in the study. MAIN OUTCOME MEASURES: CRH test results, multiple cortisol plasma concentrations, and cortisol excretion in 24-h urine were measured. RESULTS: Six (50%) of the CH-C patients had abnormal CRH test results. Three of them had discordant test results: impaired increase of plasma cortisol in response to CRH, despite substantial increase of plasma ACTH. The other three infants, with concordant impaired responses of both ACTH and cortisol to CRH, had a very low urinary cortisol excretion in comparison with the subjects with normal CRH test results. CONCLUSIONS: The CRH test proves to be a fast and reliable tool in the assessment of HPA axis (dys)function. It enables timely diagnosis in (asymptomatic) neonates at risk for serious morbidity and mortality. The discordant response type, which has not been described before, may be an early phase of HPA axis dysfunction. Alternatively, patients with this response type may constitute a separate pathogenetic subset of HPA axis-deficient patients.