Recruiting

Phenylketonuria

Sponsor:

Emory University

Code:

NCT07194993

Conditions

PKU

Eligibility Criteria

Sex: All

Age: 18+

Healthy Volunteers: Not accepted

Interventions

Nonradioactive stable oral isotope

Test diet

Study Details

Brief 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.

Conditions

PKU

Study ID

NCT07194993

Start date

Feb 16, 2026

Status verified date

May, 2026

Completion date

Aug, 2027

Anticipated

Primary completion date

Aug, 2027

Anticipated

Eligibility Criteria

Eligibility Criteria

Sex: All

Age: 18+

Healthy Volunteers: Not accepted

Inclusion Criteria:

  • 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

Exclusion Criteria:

  • 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)

Study Design

Enrollment

18 participants

Anticipated

Intervention Model

Single group

Primary purpose

Other

Interventions and Outcome Measures

Arms

experimental: Adults with PKU receiving test diet and Oral stable nonradioactive isotope provision

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.

Interventions

Nonradioactive stable oral isotope

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 diet

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.

Primary outcome measure

  • Change in rate of oxidation of tracer in the expired breath [ Time Frame: Baseline, post-intervention (3-8 hours post-baseline) ]

Central Contacts and Locations

Central contacts

Jessica Strosahl, PhD, RDN, LD

404-727-1528jessica.nash.strosahl@emory.edu

Locations

Emory University Hospital

Recruiting

Atlanta, Georgia, United States, 30322

More Information

Sponsor

Emory University

Last update posted

May 14, 2026

Last verified

May, 2026

Trial information was received from ClinicalTrials.gov and was last updated on 2026-09-10. This information was provided to ClinicalTrials.gov by Emory University on 2026-05-14.