Noninvasive surrogate markers for plasma cortisol in newborn infants: utility of urine and saliva samples and caution for venipuncture blood samples (original) (raw)

Hypothalamus-pituitary-adrenal function is associated with important physiological/pathological events in neonates. Plasma/serum cortisol levels have been used to assess hypothalamus-pituitary-adrenal function. Several noninvasive surrogate markers have been used without sufficient validation. The objectives of the study were to investigate whether plasma cortisol levels are correlated with those in saliva and urine and whether these correlations are affected by procedural pain at blood sampling. Fifty neonates were recruited from a tertiary neonatal intensive care unit. Saliva and urine samples were collected shortly before routine clinical blood sampling. Cortisol levels were compared between plasma and noninvasive samples using a linear regression analysis for the entire study population and groups, whose blood was obtained via indwelling arterial catheters (group A) or by venipuncture (group V). Predictive values of salivary/urinary cortisol for low plasma cortisol levels less t...