Phenylketonuria: Screening Programs and Testing Methods

Abstract

Comparison of the advantages and disadvantages of six different tests for phenylketonuria (PKU) reveals that all are fairly comparable in accuracy and each has enough specific merits to make it particularly valuable under certain circumstances. The tests discussed are the (1) tt test with FeCl3, (2) "diaper test" with FeCl3, (3) Phenistix (dip-stick) test, (4) filter paper test with FeCl3, (5) dinitrophenylhydrazine tt test, and (6) serum phenylalanine determination. The 1st five of these are simple urine tests. The 2d, 3d, and 4th tests are particularly suitable for mass well-baby screening programs. Active functioning well-baby screening programs have been initiated in California, Ohio and England utilizing tests (2), (4), and (3) above respectively. It is too early to draw conclusions from these studies. It is strongly advised that all mental-deficiency populations be screened for PKU, at home, in special schools, and in institutions and that the families and private physicians of diagnosed cases be alerted to this condition so that all siblings of all ages can be tested and so that subsequent siblings and cousins will be diagnosed early enough to permit maximum prevention of mental retardation from treatment with low-phenylalanine diets. Routine screening of all well-babies for PKU is essential if the maximum number of PKU infants are to be diagnosed early enough for optimum benefit from treatment.