It was noted that there might be some interference in our testing methods for patients with phenylketonuria in a survey of this institution, the Coldwater State Home and Training School. Our survey was conducted along with other institutions under the supervision of Dr. Richard Allen, Department of Pediatrics, University of Michigan Medical Center, and their Mental Study Unit.
Different urine tests were used: 1) ferric chloride; 2) Phenistix; 3) dinitrophenylhydrazine. These were added directly to fresh urine.