PKUNCT07194993
PKU Protein Requirements
A study testing Nonradioactive stable oral isotope and Test diet in people with PKU, run by Emory University at 1 site in United States.
Trial summary
The objective of this research is to determine the protein requirements based on genotype and medical food consumption in a sample of adults with Phenylketonuria (PKU) using the indicator amino acid oxidation (IAAO) method. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- PKU
- What is being tested?
- Nonradioactive stable oral isotope and Test diet
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 18 participants
- Where
- 1 siteUnited States
- Study dates
- 16 Feb 2026to Aug 2027
- Phase
- Interventional
- 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
Who may be able to join
- will be males and females (50:50) 18 years and older who were diagnosed with PKU through newborn screening or diagnosis later in life, capable of providing consent, and have previously had mutation testing
Who cannot join
- include concurrent illness, recent history of weight loss or acute illness during the past 6 months that could affect protein metabolism, pregnancy, lack of regular menstruation, implantable electronic devices or pacemakers, history of claustrophobia, and inability to provide consent. In addition, participants will be excluded if their genotype subgroup has already reached its predefined maximum enrollment (n=4)
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
United States1 site, 1 recruiting
- Recruiting
Emory University Hospital
Atlanta, Georgia, 30322
About this study
Official title: Defining Protein Requirements in Adults With PKU: Impact of Genotype and Medical Food Intake
The objective of this research is to determine the protein requirements based on genotype and medical food consumption in a sample of adults with Phenylketonuria (PKU) using the indicator amino acid oxidation (IAAO) method.
Read the detailed description
Current phenylketonuria (PKU) protein guidelines are based on outdated methods and do not account for differences in genetics or how much medical formula an individual consumes. This research aims to determine more accurate and personalized protein requirements in adults with PKU that have different genetic changes using a safe and direct method called the indicator amino acid oxidation technique. The study will address two specific aims: Aim 1 will determine the protein requirements of adults with PKU that have different genetic changes and Aim 2 will investigate how the ratio of medical formula to protein intake from natural foods affects protein needs.
Adults with PKU will be recruited for this study, and vulnerable populations will not be included.
This study includes surveys, anthropometric measurements, body composition analysis, indirect calorimetry, diet history, collection of blood, urine, and expired breath samples, administration of study day diets and an oral stable isotope protocol.
Recruitment will be at Emory Genetics Clinic. Informed consent will be obtained with an in-person signature or by an electronic IRB approved signature. Participants will attend one preliminary visit and 7 study days. Each study day will last 8 hours. Participants will be enrolled for approximately 4-6 months.
Participants will have the option to bank plasma and urine samples for future use.
- Conditions
- PKU
- Being tested
- Nonradioactive stable oral isotope, Test diet
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Nonradioactive stable oral isotopeOther
Also called Oral Isotope tracer
NaH13CO3 [99% atom percent excess (APE) and L-[1-13C]Leu (99% APE) will be given orally.
Isotope administration will begin with the fifth meal on each study day with each remaining meal.
The nonradioactive stable oral isotope is being administered to study the physiological process of amino acid oxidation.
Test dietOther
Also called Medical Food
Test diets will be provided on study days in 8 hourly isocaloric and isonitrogenous meals to maintain a metabolic steady state.
Each meal will provide one-twelfth of the participant's daily needs to model a 12-hour fasted and 12-hour fed feeding pattern.
The diet will be composed of PFD2 (Mead Johnson), Tang and Kool-Aid (Kraft), corn oil, and protein-free wheat starch cookies. Each participant will receive 1 of 7 test protein intakes (0.2-3.2 g ⋅ kg-1 ⋅ d-1) on each study day. Protein will be provided as a crystalline L-amino acid mixture based on an egg protein pattern. Phe will be provided separately based on the Phe tolerance for each patient established by the metabolic dietitian listed on the IRB protocol. Leucine will be provided at a constant amount of 82.6 mg/kg/day as it is used as the indicator amino acid. The medical food used in this study is being fed to subjects for nutritional purposes to study the oxidation of the nonradioactive oral isotope.
| Study group | Role | What they receive |
|---|---|---|
| Adults with PKU receiving test diet and Oral stable nonradioactive isotope provision | Experimental | Participants will receive amino acid tracer (Oral stable nonradioactive isotope provision) and test diet (medical food) throughout each study day, for a total of 7 study days. Receives: Other: Nonradioactive stable oral isotope; Other: Test diet |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change in rate of oxidation of tracer in the expired breath
The rate of oxidation of tracer in the expired breath will be measured in each study day.
Measured: Baseline, post-intervention (3-8 hours post-baseline)
Secondary outcomes (4)
Change in Phenylalanine concentrations before and after provision of the oral isotope protocol to provide an assessment of phenylalanine and tyrosine metabolism following study day
Phenylalanine concentration before and after provision of the oral isotope protocol to provide an assessment of phenylalanine metabolism following study day diets.
Measured: Baseline, post-intervention (8 hours post-baseline)
Change in Tyrosine concentrations before and after provision of the oral isotope
Tyrosine concentrations before and after provision of the oral isotope protocol to provide an assessment of tyrosine metabolism following study day diets.
Measured: Baseline, post-intervention (8 hours post-baseline)
Ratio of medical food protein to protein from foods protein to protein from foods
Ratio of medical food protein to protein from foods as reflected on 3-day diet records throughout the study.
Measured: Throughout the study (Up to 6 months post-intervention)
Number of participants with no adverse events related to study day diets and nonradioactive isotope tracers
Tolerability of the study day diet and the oral isotope tracer, primarily gastrointestinal tolerability will be obtained by recording the number of participants with absence of adverse events related to study day diets or nonradioactive isotope tracers.
Measured: End of study (Up to 6 months post-intervention)
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted26 Sep 2025
- Study start16 Feb 2026
- Primary completionAug 2027 (estimated)
- Study completionAug 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for PKUStudies of the same condition, open and under way.
- More trials run by Emory UniversityThe sponsor's other registered studies.
- 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
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Other
- Allocation
- Not applicable
- Intervention model
- Single group
- Model description
- The Primary purpose of this study is focused on Translational Science. The study will determine the protein requirements in one group of participants with PKU, based on genotype and medical food consumption, using the IAAO method.
- Masking
- None (open label)
- Enrolment
- 18 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Emory University
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Rani Singh, Emory University
- Investigators
- Rani Singh, PhD, RDN, LD, Principal investigator, Emory University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07194993
- Sponsor's protocol ID
- STUDY00009869
- Other IDs
- 2025P012071
- Status last verified
- May 2026
- First submitted
- 19 Sep 2025
- Last updated
- 14 May 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 14 May 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Defining Protein Requirements in Adults With PKU: Impact of Genotype and Medical Food Intake
- ClinicalTrials.gov ID
- NCT07194993
- Acronym / sponsor ID
- STUDY00009869
- Conditions
- PKU
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 18 participants (estimated)
- Lead sponsor
- Emory UniversityUniversity, hospital or other
- Study start
- 16 Feb 2026 (actual)
- Primary completion
- Aug 2027 (estimated)
- Study completion
- Aug 2027 (estimated)
- First posted
- 26 Sep 2025 (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.
The objective of this research is to determine the protein requirements based on genotype and medical food consumption in a sample of adults with Phenylketonuria (PKU) using the indicator amino acid oxidation (IAAO) method.
Detailed description
Current phenylketonuria (PKU) protein guidelines are based on outdated methods and do not account for differences in genetics or how much medical formula an individual consumes. This research aims to determine more accurate and personalized protein requirements in adults with PKU that have different genetic changes using a safe and direct method called the indicator amino acid oxidation technique. The study will address two specific aims: Aim 1 will determine the protein requirements of adults with PKU that have different genetic changes and Aim 2 will investigate how the ratio of medical formula to protein intake from natural foods affects protein needs.
Adults with PKU will be recruited for this study, and vulnerable populations will not be included.
This study includes surveys, anthropometric measurements, body composition analysis, indirect calorimetry, diet history, collection of blood, urine, and expired breath samples, administration of study day diets and an oral stable isotope protocol.
Recruitment will be at Emory Genetics Clinic. Informed consent will be obtained with an in-person signature or by an electronic IRB approved signature. Participants will attend one preliminary visit and 7 study days. Each study day will last 8 hours. Participants will be enrolled for approximately 4-6 months.
Participants will have the option to bank plasma and urine samples for future use.
Study design
- Primary purpose
- Other
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
- Model description
- The Primary purpose of this study is focused on Translational Science. The study will determine the protein requirements in one group of participants with PKU, based on genotype and medical food consumption, using the IAAO method.
| Arm | Type | Receives |
|---|---|---|
| Adults with PKU receiving test diet and Oral stable nonradioactive isotope provision | Experimental | Other: Nonradioactive stable oral isotope, Other: Test dietParticipants will receive amino acid tracer (Oral stable nonradioactive isotope provision) and test diet (medical food) throughout each study day, for a total of 7 study days. |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (1 listed)
- will be males and females (50:50) 18 years and older who were diagnosed with PKU through newborn screening or diagnosis later in life, capable of providing consent, and have previously had mutation testing
Key exclusion criteria (1 listed)
- include concurrent illness, recent history of weight loss or acute illness during the past 6 months that could affect protein metabolism, pregnancy, lack of regular menstruation, implantable electronic devices or pacemakers, history of claustrophobia, and inability to provide consent. In addition, participants will be excluded if their genotype subgroup has already reached its predefined maximum enrollment (n=4)
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Nonradioactive stable oral isotopeAlso: Oral Isotope tracerNaH13CO3 [99% atom percent excess (APE) and L-[1-13C]Leu (99% APE) will be given orally. Isotope administration will begin with the fifth meal on each study day with each remaining meal. The nonradioactive stable oral isotope is being administered to study the physiological process of amino acid oxidation. | Other | Adults with PKU receiving test diet and Oral stable nonradioactive isotope provision |
| Test dietAlso: Medical FoodTest diets will be provided on study days in 8 hourly isocaloric and isonitrogenous meals to maintain a metabolic steady state. Each meal will provide one-twelfth of the participant's daily needs to model a 12-hour fasted and 12-hour fed feeding pattern. The diet will be composed of PFD2 (Mead Johnson), Tang and Kool-Aid (Kraft), corn oil, and protein-free wheat starch cookies. Each participant will receive 1 of 7 test protein intakes (0.2-3.2 g ⋅ kg-1 ⋅ d-1) on each study day. Protein will be provided as a crystalline L-amino acid mixture based on an egg protein pattern. Phe will be provided separately based on the Phe tolerance for each patient established by the metabolic dietitian listed on the IRB protocol. Leucine will be provided at a constant amount of 82.6 mg/kg/day as it is used as the indicator amino acid. The medical food used in this study is being fed to subjects for nutritional purposes to study the oxidation of the nonradioactive oral isotope. | Other | Adults with PKU receiving test diet and Oral stable nonradioactive isotope provision |
Primary outcome
Change in rate of oxidation of tracer in the expired breath
Time frame: Baseline, post-intervention (3-8 hours post-baseline)
The rate of oxidation of tracer in the expired breath will be measured in each study day.
4 secondary outcomes
Change in Phenylalanine concentrations before and after provision of the oral isotope protocol to provide an assessment of phenylalanine and tyrosine metabolism following study day
Time frame: Baseline, post-intervention (8 hours post-baseline)
Change in Tyrosine concentrations before and after provision of the oral isotope
Time frame: Baseline, post-intervention (8 hours post-baseline)
Ratio of medical food protein to protein from foods protein to protein from foods
Time frame: Throughout the study (Up to 6 months post-intervention)
Number of participants with no adverse events related to study day diets and nonradioactive isotope tracers
Time frame: End of study (Up to 6 months post-intervention)
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 May 2026.
- Individual participant dataSharing planned: No
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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.
Rani Singh, PhD, RDN, LD principal investigator
Emory University
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Nonradioactive stable oral isotope and Test diet in people with PKU, run by Emory University at 1 site in United States.
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 1 inclusion and 1 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: looking for participants now, as of the sponsor's last update on 14 May 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 United States. 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?
Contact Jessica Strosahl, PhD, RDN, LD (404-727-1528, jessica.nash.strosahl@emory.edu), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Change in rate of oxidation of tracer in the expired breath (time frame: Baseline, post-intervention (3-8 hours post-baseline)). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
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 May 2026.