Peter Attia· MD
the traditional way we do this in the very old days believe it or not was based on on um looking at bacteria and how they would grow on an augur um that was depleted in phenyalanine and we would take a heel prick from a baby and put a little dried blood spot um punch of that dried blood spot onto a bacterial lawn and see again where the bacteria would grow so in the very old days in the late 60s early 70s we did the screen in that way