Since 2005 approximately 20 % (in total 1601 samples) of all urine specimens received for metabolic screening has been evaluated for PPD. Using our selection approach we have diagnosed seven patients, not previously suspected to have a PPD. These include: Hypoxanthine-guanine phosphoribosyltransferase (HPRT) deficiency; Adenylosuccinate lyase (ADSL) deficiency; Adenosine deaminase (ADA) deficiency and Dihydropyrimidine dehydrogenase (DPD) deficiency. Our findings highlight the importance of a selective screening approach for PPD.