Positive Neonatal Screening for Cystic Fibrosis in Neonates with Renal Failure.

Screening for cystic fibrosis (CF) was recently added to the neonatal screening programme in the Netherlands. Four patients with renal failure whose heel prick tests were positive for CF as defined by raised levels of immunoreactive trypsinogen (IRT) and pancreatitis-associated protein (PAP) are described. Both cystic fibrosis transmembrane conductance regulator (CFTR) DNA analysis and sweat tests were negative. Limited renal function can be a cause of false positive neonatal screening for CF using IRT and PAP.