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. Sweat collection was undertaken at home on both outer thigh areas using two methods (QPIT and Macroduct™). The order of testing was randomly assigned. Filter paper samples (QPIT) were analysed using flame photometry and coulometry. Macroduct™ samples were analysed using ion-selective electrodes (ISE, Abbott Architect c8000, UK). Results Insufficient sweat was collected on 28 occasions with the QPIT (coulometry) method and on 31 with the Macroduct™ (ISE) capillary system. We achieved a 92% success rate in undertaking two sweat collections consecutively (n = 177). Sweat chloride concentrations were normally distributed with excellent limits of agreement between the two methods of sweat collection and analysis (n = 150). Median (IQR) sweat chloride was 11.2 mmol/L (8–13) with QPIT (coulometry) method with a 99.5th centile (n = 165) of 24 mmol/L. Conclusion The Macroduct™ (ISE) capillary sweat collection system is valid in this age group. Sweat chloride concentrations above 30 mmol/L should prompt assessment in a specialist CF centre.

Familial pancreatic cancer (FPC) (approximately 3% of all cases) has not been linked to defects in any specific gene. Germline inactivation of the gene LKB1/STK11 have been shown to cause Peutz-Jeghers syndrome (PJS) associated with a ∼100-fold higher risk for the development of pancreatic cancer. We have analysed 39 index patients from European FPC families for mutations of LKB1/STK11 by sequencing of their DNA. No germline mutation was found within the complete coding region. Therefore, our results indicate that LKB1/STK11 is not altered in the germline of patients with hereditary pancreatic cancer.