Urinary-Free Cortisol in Hispanic and Non-Hispanic Children with Mild Asthma and Nonasthmatic Normals

Abstract

Urinary free cortisol (UFC) concentration is one of the most sensitive indicators of systemic effect of glucocorticoids. The purpose of this study was to determine normal UFC values in healthy children and children with mild asthma in a population of Hispanic and non-Hispanics. Healthy children (n = 64) and children with mild asthma (n = 36), 6 to 16 years old were recruited and admitted to a Clinical Research Center for an observed 24-hour urine collection. No differences were found for UFC (corrected or uncorrected) between healthy and patients with mild asthma or between Hispanic and non-Hispanics. The reference values for UFC/creatinine (Cr), presented as 10th–90th percentile of the mean, were 44.5 µg/g (28.3–70.4) for children with mild asthma and 44.2 µg/g (29.0–55.5) for healthy patients. Significant correlations were found between UFC and age, weight, and height. When UFC was corrected for Cr, the correlation with age and weight disappeared. When UFC was corrected for body surface area (BSA), the correlation with height and weight disappeared. Corrected UFC for Cr offers an index that is independent of age and weight of pediatric patients with no difference between Hispanics and white non-Hispanics. (Pediatr Asthma Allergy Immunol 2006; 19[2]:100–105.)