Correlation between plasma and salivary cortisol levels in preterm infants.

We sought to determine correlations between plasma and salivary cortisol levels in preterm infants in the basal state and after adrenocorticotropic hormone (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 microg/dL (P <.0001) and in saliva from 1.0 +/- 0.8 to 2.6 +/- 1.0 microg/dL (P <.0001). The adrenal response to ACTH can be detected in the saliva of premature newborns during the first week of life.