Thyroxine values from newborn screening of 919 infants born before 29 weeks' gestation.
OBJECTIVE
Severe transient hypothyroxinemia in premature infants is associated with cerebral palsy and mental retardation: this study assessed its prevalence in very premature infants.


METHODS
Congenital hypothyroidism screening programs in three states provided thyroxine values for 919 newborn infants younger than 29 weeks who were enrolled in a multicenter study.


RESULTS
Thyroxine values were lower than 4.0 micrograms/dL in 21% of survivors and increased each week by 0.6 microgram/dL (95% confidence interval [CI] = 0.4, 0.7). At tests done 1 to 2 days after birth, levels were 2.5 micrograms/dL higher (95% CI = 1.8, 3.3) than at tests done at 8 to 14 days. In New York, levels were 1.0 microgram/dL higher (95% CI = 0.3, 1.6) than elsewhere. The levels of infants who died were 1.3 micrograms/dL lower (95% CI = 0.6, 2.0) than those of survivors.


CONCLUSIONS
Severe transient hypothyroxinemia is common in very premature infants and deserves further study.
Reuss
M L
ML
Sergievsky Center, Columbia University, New York, NY, USA.
Leviton
A
A
Paneth
N
N
Susser
M
M
D005865:Gestational Age; D006801:Humans; D007226:Infant Mortality; D007231:Infant, Newborn; D007234:Infant, Premature / Q000097:blood*; D008403:Mass Screening; D015999:Multivariate Analysis; D015995:Prevalence; D013974:Thyroxine / Q000097:blood / Q000172:deficiency*; D014481:United States
D013974:Thyroxine