Aim To audit the management of congenital hypothyroidism (CHT) against the recently published national standards to identify if changes in current clinical practice are required.
Background: About 1 in 3000 babies born in the UK have congenital hypothyroidism for which a neonatal screening programme has been established since 1981. CHT is usually due to an agenesis of the thyroid gland, but some are due to dyshormogenesis, which can be transient or permanent.
Method Retrospective analysis of medical notes and electronic records of infants referred as ‘suspect’ congenital hypothyroidism from the newborn blood spot screening centre to the paediatric endocrinology service at our hospital from January 2002 to January 2013. Data collection and analysis was performed on Microsoft Excel.
Results Sixty seven infants were referred to our service, of which 33 infants had ‘confirmed’ congenital hypothyroidism’. Thyroxine was started at 12 days (median) at a dose of 8.5 mcg/kg/day (median) with a dose range from 6.1 to 11.7 mcg/kg/day. Serum Free T4 reached the upper end of reference range at 2.1 weeks (median) and Serum TSH normalised at 3.4 weeks (median) after start of treatment. Thyroid function tests were periodically monitored in the first year of life in all patients. Three infants developed significant elevation of Free T4 levels at follow up, requiring reduction of thyroxine dose. Assessment of permanence of CHT was done at three years of life in two infants who came off thyroxine. Five infants were eligible for trial off thyroxine treatment as they are receiving low doses of thyroxine with stable thyroid biochemistry.
Conclusion Although we are using less than the recommended dose of thyroxine (recommended dose is 10–15 mcg/kg/day), we are able to normalise the thyroid function tests in line with the national standards. Thus we have chosen to continue with our current starting doses. The audit has highlighted the importance of assessing permanence of congenital hypothyroidism at two to three years of age by a trial off thyroxine and checking thyroid function tests in six weeks. The new guidelines do not significantly change our current practice.