Low Beta-Adrenergic Sweat Responses in Cystic Fibrosis and Cystic Fibrosis Transmembrane Conductance Regulator-Related Metabolic Syndrome Children

beta-adrenergically stimulated sweat secretion depends on the function of the cystic fibrosis transmembrane conductance regulator (CFTR) and discriminates between cystic fibrosis (CF) patients and healthy controls. Therefore, we sought to determine the feasibility, safety, and efficacy of assaying beta-adrenergic sweating in children identified by CF newborn screening to help determine prognoses for individuals with CFTR-related metabolic syndrome (CRMS). Preschool age children with a positive newborn screening test for CF participated in this cross-sectional study. Sweat rates were measured by evaporimetery (cyberDERM, inc.) as transepidermal water losses (g H2O/m(2)/h) before and after selectively stimulating sweat glands either cholinergically or beta-adrenergically. Net peak sweat responses assayed as evaporation rates were compared between CF and CRMS cohorts. After a pilot test in adults, children between 4 and 6 years of age were evaluated (CF, n = 16; CRMS, n = 10). The test protocol was well tolerated; electrocardiograms and vital signs were within normal range for all subjects. The mean evaporative sweat rates in both groups in response to cholinergic stimulation were similar (CF, 60.3 +/- 23.8; CRMS, 57.7 +/- 13.9; p = 0.72) as well as to beta-adrenergic stimulation (CF, 1.1 +/- 1.7; CRMS, 2.0 +/- 2.0; p = 0.14). The beta-adrenergic sweat test is safe and well tolerated by young children. However, the beta-adrenergic sweat secretion rates as measured by evaporimetery did not discriminate between CF and CRMS cohorts.