PKU Protein Requirements

NCT07194993 | Not Yet Recruiting

• 1 other identifier: STUDY00009869
• Study Type: interventional
• Target: 12
• Locations: 1 country
• Sites: 1

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

Outcome Measures

Primary Outcomes (1)

• 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.

  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

  Baseline, post-intervention (8 hours post-baseline)

• Change in Tyrosine concentrations before and after provision of the oral isotope

  Baseline, post-intervention (8 hours post-baseline)

• Ratio of medical food protein to protein from foods protein to protein from foods

  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

  End of study (Up to 6 months post-intervention)

Study Arms (1)

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.

Other: Nonradioactive stable oral isotope; Other: Test diet

Interventions

Nonradioactive stable oral isotope OTHER

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.

Also known as: Oral Isotope tracer

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

Test diet OTHER

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.

Also known as: Medical Food

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

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• 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

You may not qualify if:

• 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)

Sponsors & Collaborators

• Emory University: lead

Study Sites (1)

Emory University Hospital

Atlanta, Georgia, 30322, United States

Location

Study Officials

• Rani Singh, PhD, RDN, LD

  Emory University

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Jessica Strosahl, PhD, RDN, LD

CONTACT

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

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NA
• Masking: NONE
• Purpose: OTHER
• Intervention Model: SINGLE GROUP
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Professor

Model Details: 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.

Study Record Dates

• First Submitted: September 19, 2025
• First Posted: September 26, 2025
• Study Start: February 1, 2026
• Primary Completion (Estimated): August 1, 2027
• Study Completion (Estimated): August 1, 2027
• Last Updated: January 15, 2026

Record last verified: 2026-01

Data Sharing

• IPD Sharing: Will not share

Locations

US (1)