Intervalos de referencia para tirotropina sérica durante los primeros 14 días de vida

introduction. early detection of congenital hy-pothyroidism (ch) prevents impaired cognitive and motor development at problems. to increase the screening program specifcity, we defned reference intervals for serum tsh in newborns between 2 and 14 days of life. patients and methods. newborn infants from our neonatal screening program between 2001 and 2007. serum tsh was determined by elec-trochemiluminescence. there were excluded neonates who died before the frst month of life or with less than 1500 grams at birth, samples with tsh <0,01 μu/ml., processed after 14 days of life and from other medical centers. statistical tools: student t-tests, measures of centrality and dispersion, and logarithmic transformations. results. studied population: 6772 newborn infants out of 7869, 50.49% were males. the male/ female ratio was similar during the 14 days. the mean age at testing was 5.85 days (± 2.58), and the mean of tsh value was 4.42 μu/ml (± 4.17). inverse relationship was found between age and tsh (mean tsh at days 2 and 14 was 5.82 μu/ ml and 2.58 respectively). conclusion. we found statistical evidence on an inverse relationship between tsh and age in newborn infants whit 14 days of age. reference intervals for tsh contribute to a better assessment of thyroid status in neonates and to defne an appropriate conduct for individual therapy.