1 California State Department of Public Health, Berkeley, California
Dr. Hill calls attention to the important problem of the effects of transport and storage of specimens for PKU testing, but otherwise misses the point of our article. Its purpose was to explore the pattern of PKU test results on normal newborns, considering their age in days and type of feeding and accounting for the effects of specimen age and handling, and laboratory differences. We felt that our series was large enough to be of value. Hopefully, our findings will be useful in stimulating the development, demonstration, and use of better specimen transport and holding techniques.