Etiological Grouping of Permanent Congenital Hypothyroidism with a Thyroid Gland in situ

Congenital hypothyroidism: optimal management in the light of 15 years' experience of screening.

“…This view, however, is not in line with results from the US where the New England Congenital Hypothyroidism Collaborative have reported completely normal IQ scores and school attainment up to the age of 9 years,11 1920 except in cases with early clinical features of severe congenital hypothyroidism or if compliance with treatment has been poor. These results have been taken to indicate that the effects of prenatal hypothyroidism can be completely reversed by early treatmnent and it has been suggested that the normal outcome in the New England study may be related to the use of a higher dose of thyroxine.2' Very recently, Dubuis et al in Quebec reported that 10 infants with severe hypothyroidism treated with a mean daily dose of 11 5 ,ug/kg thyroxine (mean IQ 108) did better than similar cases treated with 6-8 ,ug/kg/day (mean IQ 98). 22 Further evidence of the importance of treatment during the first year comes from Norway where Heyerdahl and her colleagues found that four children with mean plasma thyroxine concentrations below 129 nmoJIl in the first year had low IQ scores at 6 years.…”

“…In cases with a normally sited gland, we still do not try to identify the type of biosynthetic defect but specialised laboratory methods for doing this are now well established. 5 Very occasionally the 99mTc scan gives a misleading result. Over the last 15 years we have encountered a small number of cases who have had no isotope uptake in the neck but who were subsequently shown to have normal thyroid function at the time of the scan.…”

Combined ultrasound and isotope scanning is more informative in the diagnosis of congenital hypothyroidism than single scanning

“…9 10 Infants with congenital hypothyroidism due to a thyroid gland in situ show a greater diagnostic yield in terms of specific aetiology. 11 Determining the thyroid site and size by imaging is therefore desirable.…”

Ultrasound of the thyroid gland in the newborn: normative data

“…3 The discovery of the transcription factors PAX-8, TTF-1, and TTF-2 4 5 and the description of inactivating TSH receptor defects 6 7 suggest that accurate determination of thyroid anatomy will become increasingly important.…”