Thyroxine and illness severity in very low-birth-weight infants

The objective of this study was to determine the relationship between thyro xine (T-4) and illness severity in a population of preterm. infants. We inv estigated a cohort of infants with birth weights 1,500 g or less from a sin gle level III neonatal intensive care unit who received a minimum of one cr anial sonogram, to screen for intraventricular hemorrhage (IVH) and one new born screen for T-4 during a 2-year period, (n = 284). The Score for Neonat al Acute Physiology (SNAP) was used to measure illness severity- T4 and SNA P were investigated in relationship to mortality, IVH, and severe IVH. T-4 correlated inversely with SNAP (R = -0.46, p < 0.01). Infants with severe I VH and mortality had lower T-4 and higher SNAP scores when compared to infa nts without these conditions. These differences persisted after controlling for the confounding effect of gestational age. Analysis of receiver operat or curves indicated that high SNAP and low T4 were equivalently associated with IVH, severe IVH, and mortality. Our data indicate that T-4 is associat ed with illness severity in very low-birth-weight infants. Low T-4 levels a nd high SNAP scores are both associated with the outcomes of IVH and mortal ity in very low-birth-weight infants.