CASE FINDING IN PHENYLKETONURIA .2. GUTHRIE TEST

Abstract

Experience with over 6000 Guthrie tests is presented. This test is a screening procedure for phenylketonuria using small amounts of blood spotted on a filter paper which are tested by a bacterial "inhibition assay". Certain technical aspects of the test (e.g. relation between the concentration of phenylalanine in the blood and extent of the bacterial growth zones produced, type of filter paper, size of the blood spot on the paper) were investigated. It was shown that the Guthrie test clearly distinguishes between subjects with normal plasma phenylalanine levels and patients with untreated phenylketonuria. Applications of the Guthrie test in screening a mental hospital population, admissions to a penitentiary and new-born babies are described.