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Enrolling by Invitation

NCT Number: NCT07703020

Prevalence and Determinants of Obesity in PKU Patients

This observational cross-sectional multicenter study aims to assess the prevalence of overweight and obesity in adult patients with phenylketonuria (PKU) and to identify associated risk factors. Adult PKU patients followed in metabolic centers in Switzerland and Austria will be evaluated using clinical data, laboratory parameters, and standardized questionnaires addressing diet, physical activity, and psychological factors. The study seeks to better understand contributors to weight gain in this population to inform preventive strategies.

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Key information

Conditions

Phenylketonuria (PKU) Amino Acid Metabolism, Inborn Errors Body Weight Brain Diseases Brain Diseases, Metabolic Brain Diseases, Metabolic, Inborn Central Nervous System Diseases Congenital, Hereditary, and Neonatal Diseases and Abnormalities Genetic Diseases, Inborn Metabolic Diseases Metabolism, Inborn Errors Nervous System Diseases Nutrition Disorders Nutritional and Metabolic Diseases Obesity Overnutrition Overweight Pathological Conditions, Signs and Symptoms Phenylketonurias Signs and Symptoms

Age range

18 year and older

Sex eligibility

All sexes

Study type

Observational

Primary location

Lausanne University Hospital

Lausanne, Canton of Vaud, 1011, Switzerland

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Confirmed diagnosis of phenylketonuria (PKU) by biochemical and/or molecular testing.
  • Age ≥ 18 years.
  • Ability to provide written informed consent.

Exclusion criteria

  • Pregnant or lactating women.
  • Inability to follow the study procedures (e.g., due to language barriers).
  • Eligible participants who refuse to be informed of any important health concern discovered during the study.
  • Investigators, their family members, employees, or anyone with a personal link to the investigator other than a doctor-patient relationship.

Treatment and study plan

Primary outcomes

  1. Prevalence of overweight and obesity in adult PKU patients

    Time frame: At enrollment

    Defined according to WHO BMI categories (overweight: 25.0-29.9 kg/m²; obesity class I-III: ≥30.0 kg/m²)

Secondary outcomes

  1. Dietary adherence in adult PKU patients (self-reported adherence questionnaire)

    Time frame: At enrollment

    Measured as the percentage (%) of participants classified as adherent, partially adherent, or non-adherent to dietary treatment.

  2. Dietary intake in adult PKU patients (24-hour dietary recall)

    Time frame: At enrollment

    Measured as daily intake (continuous variables) including total energy (kcal/day), phenylalanine (mg/day), protein (g/day), carbohydrates (g/day), lipids (g/day), and amino acid mixtures (g/day).

  3. Disordered eating behaviors (Eating Disorder Examination Questionnaire, EDE-Q)

    Time frame: At enrollment

    Measured as global EDE-Q score (continuous scale).

  4. Depressive symptoms (Patient Health Questionnaire-9, PHQ-9)

    Time frame: At enrollment

    Measured as total PHQ-9 score (0-27). Higher scores mean worse outcomes

  5. Physical activity level (Global Physical Activity Questionnaire, GPAQ)

    Time frame: At enrollment

    Measured as total physical activity (Days-hours-minutes/week). Higher scores mean better outcome

  6. Plasma phenylalanine levels (metabolic control)

    Time frame: Retrospective (12 months prior to inclusion)

    Measured as mean phenylalanine concentration (µmol/L) over the previous 12 months

  7. Plasma tyrosine levels

    Time frame: Retrospective (12 months prior to inclusion)

    Measured as mean tyrosine concentration (µmol/L) over the previous 12 months

  8. Serum total cholesterol levels

    Time frame: Retrospective (12 months prior to inclusion)

    Measured as concentration (mmol/L) from available laboratory data.

  9. Serum triglyceride levels

    Time frame: Retrospective (12 months prior to inclusion)

    Measured as concentration (mmol/L) from available laboratory data.

  10. Blood glucose levels

    Time frame: Retrospective (12 months prior to inclusion)

    Measured as concentration (mmol/L) from available laboratory data.

  11. Thyroid-stimulating hormone (TSH) levels

    Time frame: Retrospective (12 months prior to inclusion)

    Measured as concentration (mIU/L) from available laboratory data.

  12. Vitamin B12 levels

    Time frame: Retrospective (12 months prior to inclusion)

    Measured as concentration (pmol/L) from available laboratory data.

  13. Folate (vitamin B9) levels

    Time frame: Retrospective (12 months prior to inclusion)

    Measured as concentration (nmol/L) from available laboratory data.

  14. Sapropterin treatment exposure

    Time frame: At enrollment

    Measured as percentage (%) of participants receiving sapropterin (yes/no).

Sponsors and collaborators

Lead sponsor

Christel Tran

Other

Registry information

Official study title

Phenylketonuria Associated With Obesity: a Cross-sectional Pilot Study on Prevalence and Possible Contributive Factors

Important dates

Study start
2026
Primary completion
2028
Study completion
2029
First posted
Jul 14, 2026
Registry last updated
Jul 14, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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