PKU is detected at birth through newborn screening programs — mandatory in many countries — using a simple heel-prick blood test taken within the first days of life.

What is a PKU screening test? A PKU screening test measures the amount of a protein called phenylalanine (Phe) in a sample of a newborn's blood. Phe is in all foods that contain protein such as milk, meats, and nuts. It's also in an artificial sweetener called aspartame.

Babies in the United States and many other countries are screened for PKU soon after birth. Although there is no cure for PKU, recognizing PKU and starting treatment right away can help prevent limitations in areas of thinking, understanding and communicating (intellectual disability) and major health problems.

A PKU test is a type of newborn screening that looks for signs of phenylketonuria (PKU). PKU is a genetic condition that can cause brain damage.

If you have PKU or a family history of it, your health care provider may recommend screening tests before pregnancy or birth. It's possible to identify PKU carriers through a blood test.

If you’re pregnant, a prenatal genetic test can tell you if your baby’s at risk for genetic conditions, including phenylketonuria. A genetic counselor can help you decide if testing is right for you.

In phenylketonuria (PKU), your body can't process phenylalanine, an amino acid in most foods. Read about genetics, screening, and special diets.

Blood is taken from a two-week-old baby to test for phenylketonuria PKU is commonly included in the newborn screening panel of many countries, with varied detection techniques.

What Is a PKU Test? Your newborn seems perfect. They've got 10 fingers and toes and a hearty appetite. But even healthy-looking babies can have problems you can’t see. A simple blood test looks...

Find information about newborn screening for Classic phenylketonuria, including causes, signs, symptoms, and treatment.