Salivary cortisol levels as a biomarker for severity of withdrawal in opioid-exposed newborns

Background Scoring tools used to quantify withdrawal in infants with neonatal abstinence syndrome (NAS) are often confounded by subjective measurements. This study assessed salivary cortisol as an objective biomarker of withdrawal severity in opioid-exposed newborns. Methods A prospective study was conducted in 25 full-term opioid-exposed newborns monitored for NAS. Morning and evening salivary cortisol levels were collected starting within 48 h post birth until initiation of pharmacologic treatment for withdrawal (Pre-Treatment) or when the infant was discharged without pharmacotherapy (No Treatment). Results Cortisol levels in the Pre-Treatment group ( n = 11) were significantly higher within the first week of life (median 1.74 µg/dl) than in the No Treatment group ( n = 11; median 0.72 µg/dl; P = 0.003); three infants had inadequate saliva volume for cortisol assay. Cortisol significantly decreased after 72 h post birth among infants discharged without pharmacotherapy (≤72 h median 1.25 µg/dl; ≥72 h median 0.58 µg/dl; P = 0.022), whereas cortisol remained elevated for infants subsequently treated for severity of withdrawal. No cortisol circadian rhythm was observed for either group. Conclusions Salivary cortisol in opioid-exposed newborns may provide an index of stress and help identify infants who will have more severe clinical presentation of NAS. Such a biomarker would allow risk stratification for early treatment and discharge decisions.