A reference interval for sweat chloride in infants aged between five and six weeks of age.

Background: This study was designed to establish a reference interval for sweat chloride for infants without evidence of cystic fibrosis (CF), aged between 5 wk and 6 wk, a time when sweat testing is an integral part of newborn screening for CF. In addition, we compared the gold standard method of sweat testing (quantitative pilocarpine iontophoresis [QPIT, coulometry]) with an emerging methodology (Macroduct [ISE]).

Methods: This was a prospective study on healthy infants at 5-6 wk of age.