Endocrine Abstracts

Background: Premature infants are at risk of delayed screening for congenital hypothyroidism (CH), which may markedly affect initial treatment time and neurodevelopmental outcome. Rescreening preterm infants at four weeks (30 days) of life has been recommended to detect cases with delayed TSH elevation.

Aim: To examine the performance of the CH screening programme in preterm infants aged ≤32 weeks in terms of timing of the initial Guthrie tests, and to evaluate the efficacy of rescreening in preterm infants.

Design: This retrospective study covers the period 2006–2009 inclusive. Age at initial blood spot sampling, age at repeat sampling and the prevalence of late testing in infants born ≤32 weeks’ gestation were compared with matched, randomly-selected full-term newborns. In addition, preterm infants with abnormal capillary TSH concentration (>8 mU/l) on screening who were referred to a paediatrician for evaluation were further examined. Comparing preterm infants (n=3511) with term infants (n=4000) from 2006 to 2009 showed that median (range) age for Guthrie sampling was 6 (0–223) vs 5 (4–37) days respectively (P=0.0001). Late sampling (10 days) occurred in 362 of 3511 (10.31%) preterm cases versus 12 of 4000 full term infants (0.3%). However, the overall performance was one day improved during 2008 and 2009. Twenty-six preterm infants from the whole cohort had an abnormal TSH level and seven were referred by the laboratory for further evaluation. Five of the seven infants detected on repeat screening had recorded a normal initial capillary TSH concentration.

Conclusions: Delayed capillary TSH sampling in newborns continues to pose a problem, particularly for premature infants in the Scottish screening programme despite a recent slight overall improvement in performance measure. Our finding support the rescreening of preterm infants of ≤32 weeks gestational age for detecting delayed TSH elevation.