[Routine screening for inborn errors using urine filterpaper specimens at age 4-5 weeks (author's transl)].

Since 1972 we have been using a urine screening for the detection of inborn errors of amino acid metabolism, which cannot be revealed in newborn-blood-screening with Guthrie's bacterial inhibition assay. It is performed at an age of 4-6 weeks by means of thin layer chromatography of urine specimens collected on filter paper using a method adapted by us for mass-screening. We tested 70,400 newborns and found 59 cases of incomplete Cystinuria, 9 of Prolinuria, 3 of Histidinaemia and one each of Hartnup disease, Alkaptonuria, Glycinuria and Hydroxyprolinuria. The problems of the disorders found are discussed. Comparison with newborn-blood-screening that 3 cases of Histidinaemia, proven by enzyme assay were missed by newborn-blood-screening because of their (still low) low blood levels. On the other hand we did not find additional cases of phenylalanine-metabolic disorders. These cases were probably all already detected by newborn-blood-screening. Homocystinuria, Maple syrup urine disease and Arginino-succinicaciduria which are rare diseases were neither found in the urine or blood tests. As disorders, detectable by means of urine screening exclusively and curable, are rare urine screening has to be reevaluated for its usefulness.