NCT07194993 · Emory University
PKU Protein Requirements
What this study is about
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.
View original scientific description
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.
Interventions
OTHER
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.
OTHER
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 measures
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.
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
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)
Where
- Atlanta, Georgia
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Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
Is it safe to participate?
Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
Will I be compensated?
Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
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How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced May 14, 2026 · Source of record for eligibility and locations