PKU Heel-stick screening. What is it and why it’s important Posted on October 16, 2006January 22, 2021 by rchapin Here’s a couple of links that explain PKU testing. http://www.justmommies.com/articles/heel-stick-screening.shtml http://www.webmd.com/hw/raising_a_family/hw41965.asp http://en.wikipedia.org/wiki/Phenylketonuria