Phenylketonuria (PKU)NCT07703020
Prevalence and Determinants of Obesity in PKU Patients
An observational study of Phenylketonuria (PKU), run by Christel Tran at 1 site in Switzerland.
Trial summary
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. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Phenylketonuria (PKU)
- How many people
- 100 participants
- Where
- 1 siteSwitzerland
- Study dates
- 1 Mar 2026to 1 Feb 2029
- How long will I take part?
- 2 Years
- Phase
- Observational
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Study population: Participants will be recruited from adult metabolic clinics and inherited metabolic disease centers in Switzerland (CHUV in Lausanne, HUG in Geneva, Inselspital in Bern, University Hospital Zurich, University Hospital Basel, Kantonsspital St. Gallen) and Austria (AKH Universitätsklinikum, Vienna). This population represents adults with PKU who are actively followed in specialized reference centers, reflecting a mix of patients treated since birth through newborn screening programs and those diagnosed later in life
Who may be able to join
- Confirmed diagnosis of phenylketonuria (PKU) by biochemical and/or molecular testing.
- Age ≥ 18 years.
- Ability to provide written informed consent.
Who cannot join
- 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.
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Switzerland1 site
Lausanne University Hospital
Lausanne, Canton of Vaud, 1011
About this study
Official title: Phenylketonuria Associated With Obesity: a Cross-sectional Pilot Study on Prevalence and Possible Contributive Factors
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.
- Conditions
- Phenylketonuria (PKU)
- Keywords
- phenylalanine, obesity, diet
- Medical subject headings
- Phenylketonurias, Obesity
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
| Study group | Role | What they receive |
|---|---|---|
| Adult PKU patients with overweight/obesity (BMI ≥ 25 kg/m²) | This cohort includes adult patients (≥18 years) with confirmed phenylketonuria presenting with overweight or obesity according to WHO BMI criteria. This is an observational group with no intervention. Participants will undergo a one-time assessment including standardized questionnaires evaluating physical activity (GPAQ), psychological status (PHQ-9), and eating behaviors (EDE-Q), as well as a dietary assessment (24-hour recall). Clinical, demographic, treatment-related (e.g., dietary adherence, sapropterin use), and retrospective laboratory data (e.g., phenylalanine levels and metabolic parameters) will be collected to identify factors associated with excess body weight. | |
| Adult PKU patients with normal weight (BMI <25 kg/m²) | This cohort includes adult patients (≥18 years) with confirmed phenylketonuria and normal body weight. This is an observational group with no intervention. Participants will complete the same one-time assessments as Group 1, including standardized questionnaires (GPAQ, PHQ-9, EDE-Q), dietary assessment (24-hour recall), and collection of clinical, demographic, treatment-related, and retrospective laboratory data. This group will serve as a comparator to identify factors associated with overweight and obesity in the PKU population. |
What is being measured
The primary outcome is the main question the study is designed to answer.
Prevalence of overweight and obesity in adult PKU patients
Defined according to WHO BMI categories (overweight: 25.0-29.9 kg/m²; obesity class I-III: ≥30.0 kg/m²)
Measured: At enrollment
Secondary outcomes (14)
Dietary adherence in adult PKU patients (self-reported adherence questionnaire)
Measured as the percentage (%) of participants classified as adherent, partially adherent, or non-adherent to dietary treatment.
Measured: At enrollment
Dietary intake in adult PKU patients (24-hour dietary recall)
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).
Measured: At enrollment
Disordered eating behaviors (Eating Disorder Examination Questionnaire, EDE-Q)
Measured as global EDE-Q score (continuous scale).
Measured: At enrollment
Depressive symptoms (Patient Health Questionnaire-9, PHQ-9)
Measured as total PHQ-9 score (0-27). Higher scores mean worse outcomes
Measured: At enrollment
Physical activity level (Global Physical Activity Questionnaire, GPAQ)
Measured as total physical activity (Days-hours-minutes/week). Higher scores mean better outcome
Measured: At enrollment
Plasma phenylalanine levels (metabolic control)
Measured as mean phenylalanine concentration (µmol/L) over the previous 12 months
Measured: Retrospective (12 months prior to inclusion)
Plasma tyrosine levels
Measured as mean tyrosine concentration (µmol/L) over the previous 12 months
Measured: Retrospective (12 months prior to inclusion)
Serum total cholesterol levels
Measured as concentration (mmol/L) from available laboratory data.
Measured: Retrospective (12 months prior to inclusion)
Serum triglyceride levels
Measured as concentration (mmol/L) from available laboratory data.
Measured: Retrospective (12 months prior to inclusion)
Blood glucose levels
Measured as concentration (mmol/L) from available laboratory data.
Measured: Retrospective (12 months prior to inclusion)
Thyroid-stimulating hormone (TSH) levels
Measured as concentration (mIU/L) from available laboratory data.
Measured: Retrospective (12 months prior to inclusion)
Vitamin B12 levels
Measured as concentration (pmol/L) from available laboratory data.
Measured: Retrospective (12 months prior to inclusion)
Folate (vitamin B9) levels
Measured as concentration (nmol/L) from available laboratory data.
Measured: Retrospective (12 months prior to inclusion)
Sapropterin treatment exposure
Measured as percentage (%) of participants receiving sapropterin (yes/no).
Measured: At enrollment
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted14 Jul 2026
- Study start1 Mar 2026
- Primary completion1 Feb 2028 (estimated)
- Study completion1 Feb 2029 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (1)Papers the sponsor has linked to this study.
- Other trials for Phenylketonuria (PKU)Studies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Case-control
- Time perspective
- Cross-sectional
- Enrolment
- 100 participants (estimated)
- Target duration
- 2 Years
Sponsor and investigators
- Lead sponsor
- Christel Tran
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor-investigator, Christel Tran, University of Lausanne
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07703020
- Sponsor's protocol ID
- 2024-01596
- Status last verified
- Jul 2026
- First submitted
- 24 Mar 2026
- Last updated
- 14 Jul 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: Individual participant data will not be publicly shared due to privacy and confidentiality concerns. The dataset contains sensitive personal health information, including metabolic laboratory values, dietary habits, psychological assessments, and treatment details. Although all data are coded and stored securely, sharing raw IPD could risk re-identification of participants. Aggregate results and de-identified summary data may be shared in publications or upon reasonable request, in compliance with Swiss data protection regulations.
Publications
Tankeu AT, Pavlidou DC, Superti-Furga A, Gariani K, Tran C. Overweight and obesity in adult patients with phenylketonuria: a systematic review. Orphanet J Rare Dis. 2023 Feb 22;18(1):37. doi: 10.1186/s13023-023-02636-2.
PubMed 36814307
Study at a glance
From the registry record, last updated by the sponsor on 14 Jul 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Phenylketonuria Associated With Obesity: a Cross-sectional Pilot Study on Prevalence and Possible Contributive Factors
- ClinicalTrials.gov ID
- NCT07703020
- Acronym / sponsor ID
- 2024-01596
- Conditions
- Phenylketonuria (PKU)
- Keywords
- phenylalanine, obesity, diet
- Study type
- Observational
- Recruitment status
- Enrolling by invitation
- Enrolment
- 100 participants (estimated)
- Lead sponsor
- Christel TranUniversity, hospital or other
- Study start
- 1 Mar 2026 (actual)
- Primary completion
- 1 Feb 2028 (estimated)
- Study completion
- 1 Feb 2029 (estimated)
- First posted
- 14 Jul 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
Study design
- Observational model
- Case-control
- Time perspective
- Cross-sectional
- Target follow-up
- 2 Years
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Adult PKU patients with overweight/obesity (BMI ≥ 25 kg/m²) | – | –This cohort includes adult patients (≥18 years) with confirmed phenylketonuria presenting with overweight or obesity according to WHO BMI criteria. This is an observational group with no intervention. Participants will undergo a one-time assessment including standardized questionnaires evaluating physical activity (GPAQ), psychological status (PHQ-9), and eating behaviors (EDE-Q), as well as a dietary assessment (24-hour recall). Clinical, demographic, treatment-related (e.g., dietary adherence, sapropterin use), and retrospective laboratory data (e.g., phenylalanine levels and metabolic parameters) will be collected to identify factors associated with excess body weight. |
| Adult PKU patients with normal weight (BMI <25 kg/m²) | – | –This cohort includes adult patients (≥18 years) with confirmed phenylketonuria and normal body weight. This is an observational group with no intervention. Participants will complete the same one-time assessments as Group 1, including standardized questionnaires (GPAQ, PHQ-9, EDE-Q), dietary assessment (24-hour recall), and collection of clinical, demographic, treatment-related, and retrospective laboratory data. This group will serve as a comparator to identify factors associated with overweight and obesity in the PKU population. |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
- Study population
- Participants will be recruited from adult metabolic clinics and inherited metabolic disease centers in Switzerland (CHUV in Lausanne, HUG in Geneva, Inselspital in Bern, University Hospital Zurich, University Hospital Basel, Kantonsspital St. Gallen) and Austria (AKH Universitätsklinikum, Vienna). This population represents adults with PKU who are actively followed in specialized reference centers, reflecting a mix of patients treated since birth through newborn screening programs and those diagnosed later in life
Key inclusion criteria (3 listed)
- Confirmed diagnosis of phenylketonuria (PKU) by biochemical and/or molecular testing.
- Age ≥ 18 years.
- Ability to provide written informed consent.
Key exclusion criteria (4 listed)
- 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.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Primary outcome
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)
14 secondary outcomes
Dietary adherence in adult PKU patients (self-reported adherence questionnaire)
Time frame: At enrollment
Dietary intake in adult PKU patients (24-hour dietary recall)
Time frame: At enrollment
Disordered eating behaviors (Eating Disorder Examination Questionnaire, EDE-Q)
Time frame: At enrollment
Depressive symptoms (Patient Health Questionnaire-9, PHQ-9)
Time frame: At enrollment
Physical activity level (Global Physical Activity Questionnaire, GPAQ)
Time frame: At enrollment
Plasma phenylalanine levels (metabolic control)
Time frame: Retrospective (12 months prior to inclusion)
Plasma tyrosine levels
Time frame: Retrospective (12 months prior to inclusion)
Serum total cholesterol levels
Time frame: Retrospective (12 months prior to inclusion)
Serum triglyceride levels
Time frame: Retrospective (12 months prior to inclusion)
Blood glucose levels
Time frame: Retrospective (12 months prior to inclusion)
Thyroid-stimulating hormone (TSH) levels
Time frame: Retrospective (12 months prior to inclusion)
Vitamin B12 levels
Time frame: Retrospective (12 months prior to inclusion)
Folate (vitamin B9) levels
Time frame: Retrospective (12 months prior to inclusion)
Sapropterin treatment exposure
Time frame: At enrollment
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 14 Jul 2026.
- Background: PubMed 36814307Tankeu AT, Pavlidou DC, Superti-Furga A, Gariani K, Tran C. Overweight and obesity in adult patients with phenylketonuria: a systematic review. Orphanet J Rare Dis. 2023 Feb 22;18(1):37. doi: 10.1186/s13023-023-02636-2.
- Individual participant dataSharing planned: No. Individual participant data will not be publicly shared due to privacy and confidentiality concerns. The dataset contains sensitive personal health information, including metabolic laboratory values, dietary habits, psychological assessments, and treatment details. Although all data are coded and stored securely, sharing raw IPD could risk re-identification of participants. Aggregate results and de-identified summary data may be shared in publications or upon reasonable request, in compliance with Swiss data protection regulations.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Phenylketonuria (PKU), run by Christel Tran at 1 site in Switzerland.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 3 inclusion and 4 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: enrolling by invitation, as of the sponsor's last update on 14 Jul 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Switzerland. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Prevalence of overweight and obesity in adult PKU patients (time frame: At enrollment). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT07703020, which also lists 1 linked publication.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 14 Jul 2026.