PKU Protein Requirements

Conditions

• PKU

Eligibility Criteria

Sex

ALL

Age

18 Years - N/A

Healthy Volunteers

Not accepted

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.
• 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.

Study Details

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.

Key Dates

Start date

Feb 16, 2026

Status verified

May 2026

Primary completion

Aug 31, 2027

Completion

Aug 31, 2027

Study Design

Enrollment

18 participants (estimated)

Allocation

NA

Intervention model

SINGLE_GROUP

Primary purpose

OTHER

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.

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

• Jessica Strosahl, PhD, RDN, LD
  404-727-1528
  [email protected]

Locations (1)

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