Orthostatic proteinuria and the spectrum of diurnal variability of urinary protein excretion in healthy children.

The aim of this study was to characterize the 24-h and diurnal variability of urinary protein excretion and identify the prevalence of orthostatic proteinuria (OP) in healthy children. Upright, supine, and 24-h total urinary protein (UrTP) and creatinine clearance (CrCl) were measured in 91 healthy children ages 6-19 years. Urinary protein and creatinine excretions were calculated and examined by gender, age, Tanner stage, and body mass index (BMI). Orthostatic proteinuria (OP) was defined as a 24-h UrTP >100 mg/m(2) with a normal supine UrTP (<4 mg/m(2)/h). There exists a marked diurnal variability in UrTP. The upright UrTP rate was three to four-times greater than the supine rate. UrTP, adjusted for body surface area, is higher in boys than girls and increases with age and BMI. There is a similar increase in upright CrCl compared with supine. Urinary protein to creatinine ratio (UPcr) is strongly correlated with UrTP. OP is common, being found in 20% of children in this cohort, and is more common in boys and associated with age >10 years and BMI >85%. In children with OP, a first morning UPcr shows a value in the normal range, whereas a random daytime UPcr is elevated. There exists a diurnal variability in urinary protein excretion that is exaggerated in participants with OP. UPcr reliably estimates 24-h UrTP. Using current pediatric criteria, OP is very common, particularly in boys. A normal first morning UPcr ratio indicates that a child with elevated random urinary protein has OP.

Pretreatment with albuterol versus montelukast for exercise-induced bronchospasm in children.

STUDY OBJECTIVES: To compare pretreatment with albuterol versus montelukast added to the current asthma regimen for protection against exercise-induced bronchospasm in children with mild-to-moderate asthma, and to determine whether cysteinyl leukotriene (Cys-LT) concentrations measured in the exhaled breath condensate correlated with response to montelukast. DESIGN: Prospective, randomized, double-blind, double-dummy, crossover study. SETTING: Asthma clinic at a university-affiliated medical center. PATIENTS: Eleven children aged 7-17 years with physician-diagnosed mild-to-moderate asthma for at least 6 months and with self-reported exercise-induced bronchospasm (defined as > or = 15% decrease in forced expiratory volume in 1 sec [FEV(1)] at screening and baseline visit). INTERVENTION: Patients were randomly assigned to receive 3-7 days of oral montelukast 5-10 mg/day or 2 puffs of an albuterol metered-dose inhaler just before an exercise challenge and then were crossed over to the alternate therapy for the last visit. MEASUREMENTS AND MAIN RESULTS: Serial spirometry was performed before and at 0, 5, 10, 15, 30, 45, and 60 minutes after the exercise challenge at each visit. Measurement of exhaled breath condensate was performed at the screening visit and study visits 1 and 2. The primary outcome was the maximum change in FEV(1) after exercise. Secondary outcomes were the area under the curve for FEV(1) (expressed as percentage decrease from baseline) during the first 60 minutes (AUC(0-60)) after exercise and the proportion of patients in whom exercise-induced bronchospasm was prevented (defined as < 15% decrease in FEV(1) after exercise challenge). The mean +/- SD maximum decrease in FEV(1) was 27.5 +/- 7.9% at baseline. Patients receiving montelukast had an 18.3 +/- 13.7% decrease in FEV(1) compared with 0.7 +/- 1.6% in patients receiving albuterol (p=0.002, paired t test). Exercise-induced bronchospasm was prevented in 100% of the patients receiving albuterol compared with 55% receiving montelukast (p<0.05, McNemar's test). The AUC(0-60) was significantly smaller with albuterol compared with montelukast (p<0.001, Wilcoxon signed rank test). No correlations were found between Cys-LT concentration and the severity of exercise-induced bronchospasm or the response to montelukast. CONCLUSION: Pretreatment with albuterol is more effective than montelukast for prevention of exercise-induced bronchospasm in children with asthma.