Testing of all newborn infants for certain disorders is now mandatory in California. Blood tests for phenylketonuria (PKU), galactosemia, and hypothyroidism, performed around the second day of life, have been found to be accurate and cost-effective. The early identification of these disorders may lead to appropriate therapy, but without detection serious mental retardation or death may occur. In California, screening for galactosemia is done by fluorescent measurement of the enzyme galactose-1-phosphate uridyl transferase1 (gal-1-PUT) and by semiquantitative measurement of blood galactose through Escherichia coli inhibition.2,3 We studied the case of an infant with galactosemia who, at the initial screening, had normal levels of blood galactose.
Report of a Case.—A 3,570-g, white female infant was the first child born to a nonconsanguinous 29-year-old woman and her 31-year-old husband. The pregnancy, labor, and delivery were normal. Routine newborn screening tests for PKU, galactosemia, and hypothyroidism were performed on the