Home›Medicine & Health›Diseases & Conditions (continued)›What is Phenylketonuria (PKU)?
◎ Medicine & Health·2 min·Updated Mar 15, 2026

What is Phenylketonuria (PKU)?

Phenylketonuria

Quick Answer

This is a rare genetic disorder that affects how the body processes a specific amino acid called phenylalanine. If not managed properly, it can lead to serious health issues, including intellectual disability.

Overview

Phenylketonuria, often abbreviated as PKU, is a genetic condition where the body cannot break down phenylalanine, an amino acid found in many protein-rich foods. Normally, an enzyme called phenylalanine hydroxylase helps convert phenylalanine into another amino acid called tyrosine. Without this enzyme, phenylalanine builds up in the body, which can cause brain damage and other serious health problems if not treated early. Managing PKU involves a strict diet that limits high-protein foods like meat, fish, eggs, dairy, and nuts, which are high in phenylalanine. Instead, individuals with PKU often consume special medical formulas that provide the necessary nutrients without the harmful amino acid. For example, a child with PKU may eat fruits and vegetables while avoiding bread and pasta made from wheat, which contains phenylalanine. PKU is significant because it can lead to developmental issues if not detected and managed early. Newborn screening programs in many countries test for PKU shortly after birth, allowing for early intervention. This early diagnosis and dietary management can help those with PKU lead healthy, normal lives.

Frequently Asked Questions

PKU is caused by a mutation in the gene that provides instructions for making the enzyme phenylalanine hydroxylase. This mutation leads to a deficiency or absence of the enzyme, preventing the body from breaking down phenylalanine.
PKU is typically diagnosed through newborn screening tests that check for high levels of phenylalanine in the blood. If the test indicates a problem, further tests are conducted to confirm the diagnosis.
While there is no cure for PKU, it can be effectively managed through a strict diet that limits phenylalanine intake. Regular monitoring and dietary adjustments are essential to keep phenylalanine levels within a safe range.