Phenylketonuria (PKU) is an inherited inborn error of phenylalanine (PHE) metabolism caused by decreased activity of phenylalanine hydroxylase (PAH) enzyme. Therefore, PHE accumulates in plasma leading to mental problems. Treatment is a phenylalanine-restricted diet with sufficient protein. However, the optimum protein requirements are still unknown and compliance with diet is not satisfactory in PKU adults. A Previously established technique called indicator amino acid oxidation (IAAO) will be used to determine protein requirements from amino acid based formula vs. glycomacropeptide (GMP) in adults with PKU (≥ 19y). This study will help treat adults with enough protein ensuring maintenance of health.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
SUPPORTIVE_CARE
Masking
NONE
Enrollment
6
Oral consumption of eight hourly experimental meals- -4 tracer free experimental meals containing a mixture of free amino acids and calories from protein free flavoured liquid, protein free cookies and corn oil -4 isotopically labeled experimental meals. The same protocol will be repeated with glycomacropeptide (GMP).
BC Children's Hospital Research Institute, University of British Columbia
Vancouver, British Columbia, Canada
13 Co2 production
Breath samples will be collected during the study to measure the rate of oxidation of tracer in the expired breath.
Time frame: 8 hours (1 study day). 3 samples will collected as a baseline prior to isotope protocol and 6 samples after 2 hours and 30 minutes of starting the tracer protocol. Data will be reported an average of 2 years.
Lysine flux
Urine samples will be collected during the study to measure the flux enrichment in urine.
Time frame: 8 hours (1 study day). 1 sample will collected as a baseline prior to isotope protocol and 2 samples after 2 hours and 30 minutes of starting the tracer protocol. Data will be reported an average of 2 years.
Phenylalanine concentrations
Phenylalanine concentrations will be measured in blood.
Time frame: One sample (at 6th meal) after starting of the tracer protocol. Data will be reported an average of 2 years.
Tyrosine concentrations
Tyrosine concentrations will be measured in blood.
Time frame: One sample (at 6th meal) after starting of the tracer protocol. Data will be reported an average of 2 years.
16 other amino acids
16 other amino acids will be measured in blood.
Time frame: One sample (at 6th meal) after starting of the tracer protocol. Data will be reported an average of 2 years.
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