Inclusion Criteria (patient with PKU)  Age >/= 18 years old Phenylketonuria diagnosis Fasting condition Registered with a social security system Patient consent  Inclusion Criteria (healthy volunteer)  Age >/= 18 years old No metabolic condition Fasting condition Paired to patient with phenylketonuria already included according to age, sex and BMI class Registered with a social security system Volunteer consent  Exclusion Criteria, common to healthy volunteer and patient with phenylketonuria  Pregnant and lactating women Subject to legal protection measures. Chronic or acute inflammatory disease Fever on inclusion Undergoing anti inflammatory treatment Surgery in the previous months Diabetes Included in other therapeutic trial