116 adults and older children. The correla- tion between serum and salivary cortisol levels is well-established in these pa- tients. 6 However, there are few investi- gations of salivary cortisol in term newborns, 7-10 and no measurements in preterm infants have been reported. Our objective was to determine whether plasma and salivary cortisol levels correlated in preterm infants be- fore and after ACTH stimulation. METHODS Preterm infants (n = 48) were select- ed consecutively from patients admitted to the nursery of Hospital das Clínicas de Ribeirão Preto, University of São Paulo, Brazil, if they met the following criteria: (1) gestational age was be- tween 25 and 34 weeks as determined by the Ballard score, 11 (2) postnatal age was 3 to 7 days, (3) absence of congeni- tal malformations, (4) stable cardio- respiratory condition, (5) no previous treatment with corticoids, and (6) mothers who had not used corticoids or had gestational diabetes. The study and the information protocol were approved by the hospital Ethics Committee and informed consent was obtained from the parents. Cortisol is important during fetal matu- ration and preparation for extrauterine life. Fetal cortisol concentration in- creases during the last 10 weeks of ges- tation. Increased cortisol promotes pulmonary surfactant synthesis, in- creases hepatic thyroxine to triiodothy- ronine conversion, decreases sensitivity of the ductus arteriosus to prosta- glandin that facilitates its closure, and induces maturation of several enzymes and transportation processes in the small intestine. 1 Correlation between plasma and salivary cortisol levels in preterm infants Cristina Calixto, MD, Francisco E. Martinez, MD, Salim M. Jorge, MD, Ayrton C. Moreira, MD, and Carlos E. Martinelli Jr, MD From the Departments of Medicine and Pediatrics, Hospital das Clínicas, School of Medicine, Ribeirão Preto, University of São Paulo, Brazil. Supported by CAPES: Fundação Coordenação de Aperfeiçoamento de Pessoal de Nível Superior. Submitted for publication Nov 3, 2000; revisions received Mar 30, 2001, and May 3, 2001; accepted Sept 28, 2001. Reprint requests: Cristina Calixto, School of Medicine of Ribeirão Preto, University of São Paulo, Av dos Bandeirantes 3900, CEP: 14049-900, Ribeirão Preto-São Paulo, Brazil. Copyright © 2002 by Mosby, Inc. 0022-3476/2002/$35.00 + 0 9/22/120765 doi:10.1067/mpd.2002.120765 ACTH Adrenocorticotropic hormone CV Coefficient of variation Preterm infants have a limited capaci- ty to respond to stress; thus, adrenal in- sufficiency develops and the infant requires cortisol supplementation. 2,3 The standard procedure for evaluating hypo- thalamus-pituitary-adrenal function is the determination of serum cortisol at basal levels and 60 minutes after adreno- corticotropic hormone (ACTH) stimula- tion. 4,5 Because saliva collection is easy to perform and reliable, salivary concen- trations of cortisol are frequently used to evaluate adrenal cortex function in We sought to determine correlations between plasma and salivary cortisol levels in preterm infants in the basal state and after adrenocorticotropic hor- mone (ACTH) stimulation during the first week of life. Infants (n = 48) were given ACTH or saline solution; each injection was separated by 24 hours. Salivary and plasma cortisol levels correlated at baseline (r = 0.67, P < .0001) and 1 hour after ACTH stimulation (r = 0.40, P = .0047). ACTH increased cortisol levels in plasma from 12.3 ± 6.4 to 30.3 ± 13.2 μg/dL (P < .0001) and in saliva from 1.0 ± 0.8 to 2.6 ± 1.0 μg/dL (P < .0001). The adrenal response to ACTH can be detected in the saliva of premature newborns during the first week of life. (J Pediatr 2002;140:116-8) C LINICAL AND L ABORATORY O BSERVATIONS