Very low birth weight newborns do not need repeat screening for congenital hypothyroidism.
OBJECTIVE
To determine whether repeat screening for congenital hypothyroidism is necessary in newborns weighing <1500 g (very low birth weight [VLBW]).


METHODS
All VLBW infants born in the province of Québec between October 15, 1993, and October 15, 1994, had a second filter paper sample requested at 6 weeks of age to measure thyrotropin and thyroxine, in addition to these measurements for the routine screening sample. We then conducted a survey of all 4 academic pediatric endocrinology clinics in the province, inquiring about cases of permanent primary congenital hypothyroidism (PPCH) in children born weighing <1500 g or who may have been missed by neonatal screening.


RESULTS
Two specimens were obtained in 465 VLBW newborns. One case of mild transient hyperthyrotropinemia was identified. The survey identified 4 VLBW newborns with PPCH: 1 girl and 1 boy with dyshormonogenesis, 1 athyreotic girl, and 1 girl with thyroid ectopy. All 4 were detected by their initial filter paper specimens. The survey also identified 1 case of PPCH in a girl who had a normal neonatal screen and normal birth weight.


CONCLUSIONS
VLBW newborns with PPCH can mount an appropriate thyrotropin response and do not need repeat screening for congenital hypothyroidism.
Vincent
Melanie A
MA
Hôpital Sainte-Justine, Université de Montréal, Montréal, Québec, Canada.
Rodd
Celia
C
Dussault
Jean H
JH
Van Vliet
Guy
G
D003409:Congenital Hypothyroidism; D005260:Female; D006801:Humans; D007037:Hypothyroidism / Q000175:diagnosis*; D007231:Infant, Newborn; D007235:Infant, Premature, Diseases / Q000175:diagnosis*; D019102:Infant, Very Low Birth Weight; D008297:Male; D015997:Neonatal Screening / Q000379:methods; D013960:Thyroid Function Tests / Q000379:methods