[Using newborn congenital hypothyroidism screening specimens to detect iodine deficiency in three regions of Spain].
BACKGROUND
Neonatal hyperthyrotropinemia by measurements of thyrotropin (TSH) concentrations has been assessed in three different areas of Spain. The repercussions of a possible iodine deficiency in a congenital hypothyroidism screening program have also been analysed


METHODS
The study comprised 113,108 newborns, which were divided into two groups according to the time of blood sampling. In 78,646 newborns heel blood samples were obtained after 48h whereas in 34,462 newborns, samples were obtained at birth from the umbilical cord (early samples). Newborns came from three areas of the south of Spain, Seville, Huelva and Cordoba. TSH concentrations were measured by time-resolved fluoroimmunoassay.


RESULTS
The percentage of hyperthyrotropinemia was greater in Huelva (5.2%) than Seville (1.0%) (p<0.001), similar to that observed in early samples, which was higher in Huelva (5.3%) than in Seville (1.9%) and Cordoba (1.7%) (p<0.001). In the early samples group, 0.3% and 0.2% of the newborns from Seville and Cordoba respectively, had TSH >20mIU/L and 10 infants should have been recalled for a new sample for each case detected. While in Huelva 17 infants (0.9%) were recalled per case detected.


CONCLUSIONS
The heterogeneous distribution of TSH concentrations in newborns from several geographical areas appears to indicate an irregular and deficient iodine intake. Using early samples and a possible iodine deficiency, increase false positive results in a Neonatal Screening Program of congenital hypothyroidism.
Velilla
T Arrobas
TA
Departamento de Bioquímica Clínica, Hospital Universitario Virgen Macarena, Sevilla, España.
Rodríguez
C González
CG
Sánchez
A Barco
AB
Portillo
C Morales
CM
de la Vega
J A Bermúdez
JA
Cerrato
S Bernal
SB
Baldrich
A Gentil
AG
Montávez
J M Guerrero
JM
Pérez
A Sendón
AS
Arriero
J M González de Buitrago
JM
Ortiz
R Goberna
RG
D005260:Female; D006801:Humans; D007037:Hypothyroidism / Q000453:epidemiology*; D007231:Infant, Newborn; D007455:Iodine / Q000172:deficiency*; D008297:Male; D008403:Mass Screening / Q000379:methods*; D015995:Prevalence; D013030:Spain / Q000453:epidemiology; D013972:Thyrotropin / Q000097:blood*
D013972:Thyrotropin; D007455:Iodine