26 years of external quality controls for the screening of congenital metabolic disorders in newborns--a summary of the results.

The evaluation of the inter-laboratory tests over the 26 year period shows a clear improvement in the analysis quality of the test participants. This can be clearly seen in the increased recovery rates of the pathological quality control samples. Centers are put in the position to adjust their own quality control measures for their analysis to international standards, thereby decreasing the error rate in their analyses. The introduction of the tandem mass spectrometer for newborn screening is inevitably connected to even higher requirements in the quality of the measured values. Up to now, though, commercially or scientifically determined external quality controls do not exist. In November 2005, as a start, we tentatively expanded our (since 1982) existing inter-laboratory controls to include parameters determinable by mass spectrometry. A second external control will take place in May 2008 for acylcarnitines.