Urinary free cortisol (UFC) values in newborns under stress

Children with adrenocortical insufficiency are commonly instructed to incre ase three to five times baseline glucocorticoid replacement dose during per iods of stress such as surgery or febrile illness. The present study was un dertaken to determine whether these recommendations reflect the actual chan ge in urinary free cortisol (UFC) output during stress in neonates and to t est the effect of stress on the diurnal variation of cortisol in this age g roup. Design and patients: Twenty-four hour urinary free cortisol (UFC) excretion was determined in 75 neonates during the first 2 days of life. Thirty were healthy and 45 were neonates with respiratory distress. In 60 babies the 2 4-h UFC was collected in 6-h fractions for the determination of diurnal var iation of urinary cortisol. Results: The mean change in UFC was 4.5 times higher in the sick babies tha n in the controls. A distinct diurnal variation of UFC was noted in both he althy and sick babies. Conclusions: In contrast with previous publications a distinct diurnal patt ern was noted in the majority of neonates.