NCT07194993

PKU Protein Requirements

Defining Protein Requirements in Adults With PKU: Impact of Genotype and Medical Food Intake

• Status: Not Yet Recruiting
• Phase: N/A
• Study type: Interventional
• Enrollment: 12 (estimated)
• Sponsor: Emory University · Academic / Other
• Sex: All
• Age: 18 Years
• Healthy volunteers: Not accepted

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.

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Current phenylketonuria (PKU) protein guidelines are based on outdated methods and do not account for differences in genetics or how much medical formula an individual consumes.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

Interventions

Type	Name	Description
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.

Timeline

• Start date: 2026-02-01
• Primary completion: 2027-08-01
• Completion: 2027-08-01
• First posted: 2025-09-26
• Last updated: 2026-01-15

Locations

1 site across 1 country: United States