Endocrine Abstracts

Introduction: Congenital hypothyroidism (CHT) has a reported incidence of 1:3500 in Caucasian populations. Early detection by newborn screening and appropriate L-thyroxine treatment leads to normal or near-normal neurocognitive outcome.

The National Newborn screening programme (NNP) was established in Children’s University Hospital, Temple St. in 1979. This study aimed to ascertain the incidence of congenital hypothyroidism in the Republic of Ireland (ROI) and to evaluate the screening programme with regard to time taken to diagnosis, initiation of treatment and the contribution of scanning to diagnosis.

Methods: An audit was performed of all positive screens for CHT between July 1979 and December 2008. Date of detection, clinical presentation, thyroid function tests and technetium scan results (from 1990) were reviewed.

Results: A total of 648 children have been diagnosed with CHT. The incidence of CHT was 1 case per 2296 live births in the Republic of Ireland (ROI) in the past decade with increasing numbers over recent years. Sixty five percent of cases were female (male =221, female =403, unreported =24). A median of 22 cases were reported annually (range 14–44). The median time to sample collection was 5 days and median time to detection of an abnormal sample was 9 days. Scan information was available on 368/459 cases screened since 1990 discriminating between thyroid agenesis (n=87), ectopic/small thyroid (n=164), dyshormonogenesis (n=58), and normally placed thyroids (n=59). Mean TSH on screening card compared to scan results were 230 mU/l (agenesis), 162 mU/l (ectopic thyroid), 60mU/l (dyshormonogenesis) and 78 mU/l (normal thyroid).

Conclusions: The CHT screening programme has been successful in the early detection of affected cases. A target time of 10 days is been evaluated. Reasons for the increase in incidence of CHT in recent years require further investigation.