Endogenous Glucocorticoid Response to Single-Dose Dexamethasone for Croup in Children: A Pharmacodynamic Study.

OBJECTIVES: Dexamethasone is associated with adrenal insufficiency in adults and children with chronic disease. This association has not been studied after single-dose oral dexamethasone, the standard of care for children with croup. We hypothesized that single-dose oral dexamethasone in children with croup is associated with a transient decrease in endogenous glucocorticoids. METHODS: We conducted a prospective, 2-arm, pharmacodynamic study of single-dose oral dexamethasone 0.6 mg/kg (maximum, 12 mg) in children older than 2 years with croup compared with controls (children with febrile upper respiratory tract infections who did not receive dexamethasone). Primary outcome was urinary 6ß-hydroxycortisol-cortisol ratio. RESULTS: Twenty-seven children were analyzed (22 with croup and 5 with upper respiratory tract infections). Median 6ß-hydroxycortisol-cortisol ratios before dexamethasone, the following morning, and on days 1, 3, and 7 were 2.8, 2.2, 2.0, 2.8, and 2.6, respectively. Among controls, the median 6ß-hydroxycortisol-cortisol ratios at the same time intervals was 1.9, 1.5, 1.8, 2.5, and 1.7, respectively. There were no significant differences in the change from time 0 between groups at any time point. There were no serious adverse events or infectious complications. CONCLUSIONS: Single-dose oral dexamethasone is not associated with decreased endogenous corticosteroid levels in children with croup. Future studies should use criterion standard tests to rule out suppression of the hypothalamic-pituitary-adrenal axis and be powered sufficiently to identify adverse clinical outcomes.

Metabolomics for the identification of early biomarkers of nephrotoxicity in a mouse model of cisplatin-induced acute kidney injury.

BACKGROUND AND PURPOSE: Cisplatin-induced nephrotoxicity manifests as acute kidney injury (AKI) in approximately one third of patients receiving cisplatin therapy. Current measures of AKI are inadequate in detecting AKI prior to significant renal injury, and better biomarkers are needed for early diagnosis of cisplatin-induced AKI. EXPERIMENTAL APPROACH: C57BL/6 and FVB/N mice were treated with a single intraperitoneal injection of cisplatin (15 mg kg-1) or saline. Plasma, urine, and kidney samples were collected prior to cisplatin injection and 24-, 48-, 72-, and 96-hours following cisplatin injection. Untargeted metabolomics was employed using liquid chromatography-mass spectrometry to identify early diagnostic biomarkers for cisplatin nephrotoxicity. PRINCIPAL RESULTS: There was clear metabolic discrimination between saline and cisplatin-treated mice at all timepoints (day 1 to day 4). In total, 26 plasma, urine, and kidney metabolites were identified as exhibiting early alterations following cisplatin treatment. Several of the metabolites showing early alterations were associated with mitochondrial function and energetics, including intermediates of the tricarboxylic acid cycle, regulators of mitochondrial function and indicators of fatty acid ß-oxidation dysfunction. Furthermore, several metabolites were derived from the gut microbiome. MAJOR CONCLUSIONS: Our results highlight the detrimental effects of cisplatin on mitochondrial function and demonstrate potential involvement of the gut microbiome in the pathophysiology of cisplatin-induced AKI. We provide a panel of metabolites to guide future clinical studies of cisplatin-induced AKI and provide insight into potential mechanisms behind cisplatin nephrotoxicity.