Newborn screening for congenital hypothyroidism in early discharged infants.

A study of newborn thyroid stimulating hormone (TSH) levels was undertaken to determine whether a quantitative relationship exists between TSH values obtained between the 12th to 24th hours of life and the 48th to 72nd hours of life. The study was designed to: (a) measure TSH levels in full term newborns between the 12th - 24th hours of life, (b) measure TSH levels in the same set of newborns at 48 - 72 hours of life, (c) correlate TSH values obtained during the two time periods of specimen collection, (d) determine whether TSH results at 12 to 24 hours are predictive of TSH levels at 8 to 72 hours, and (e) determine the effects of other factors on TSH 48-72. One thousand three hundred seventy full term normal infants delivered at the Philippine General Hospital and at the Rizal Medical Center from August 1999 to March 2001 participated in the study. Eighty-three percent were from Metro Manila and the rest from the provinces. Although there was a significant association between TSH12-24 and TSH48-72, the magnitude of association could not account for all of the variance in the TSH48-72 values. By itself, TSH12-24 cannot clinically predict 48-72 hour TSH levels. Multiple regression analysis showed that sex and mode of delivery by cesarean section were significant factors affecting TSH levels at 48-72 hours.