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Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Type of registration
Retrospectively registered

Titles & IDs
Public title
Uptake kinetics of dietary phenylalanine during continuous enteral feeding
Scientific title
Uptake kinetics of dietary 13C-phenylalanine during continuous enteral feeding in healthy subjects
Secondary ID [1] 288978 0
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Enteral feeding 298371 0
Condition category
Condition code
Diet and Nutrition 298475 298475 0 0
Other diet and nutrition disorders

Study type
Description of intervention(s) / exposure
During development of a methodology for studying enteral nutrition in ICU patients (see trial ID ACTRN12614000476639) we studied a pilot group of ICU patients to determine uptake kinetics of dietary stable-isotope-labeled phenylalanine during continuous enteral feeding. Relevant findings were a high inter-individual variability of 13C-phenylalanine plasma enrichment and uncertain steady state condition after 6 hrs of feeding (unpublished data).

The objective of the current trial is to determine whether a steady state of 13C-phenylalanine isotopic enrichment in plasma is reached after 6, 8, 10 or 12 hrs of 13-C-phenylalanine administration simultaneous with continuous enteral feeding. Subjects are admitted on the evening before the tracer study and stay under observation throughout the experiment. A nasogastric feeding tube is placed and a continuous infusion of a commercially available complete nutrition formula, Fresubin (registered trademark) Original, is started at a dose corresponding to 100% of estimated energy requirement. After a 12 hr equilibration period, a cannula for blood sampling is placed in an artery. Ongoing continuous nutrition is supplemented with a continuous infusion of 13C-labeled phenylalanine for another 12 hrs. The 13C-phenylalanine dose is calculated to yield an isotopic enrichment of 30.8% of the total dietary phenylalanine content, i.e. feeding formula + tracer Blood samples are taken every 30 minutes for the remaining 12 hrs. Isotopic enrichment of 13C-phenylalanine in plasma is measured by gas chromatography-mass spectrometry.
Intervention code [1] 294464 0
Treatment: Other
Comparator / control treatment
No control group
Control group

Primary outcome [1] 297963 0
Plasma enrichment of 13C-phenylalanine
Timepoint [1] 297963 0
Every 30 minutes from 12 to 24 hours post commencement of continuous enteral feeding
Secondary outcome [1] 322777 0
Timepoint [1] 322777 0

Key inclusion criteria
Healthy adults
Minimum age
18 Years
Maximum age
No limit
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
Nutritional/metabolic disease, serious organ dysfunction

Study design
Purpose of the study
Allocation to intervention
Non-randomised trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Masking / blinding
Open (masking not used)
Who is / are masked / blinded?

Intervention assignment
Single group
Other design features
Not Applicable
Type of endpoint(s)
Statistical methods / analysis
Results are analysed both per individual and for pooled data from the whole cohort. The primary question is whether isotopic enrichement of 13C-Phe reaches a steady state. This can be analysed by linear regression over a set of timepoints to determine whether there is a gradient over time that is significantly different from zero.

A sample size calculation is not made because the effect size is not known and can not be estimated with sufficient reliability from existing data.

Recruitment status
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment outside Australia
Country [1] 7804 0
State/province [1] 7804 0

Funding & Sponsors
Funding source category [1] 293334 0
Government body
Name [1] 293334 0
Regional Agreement on Medical Training and Clinical Research (ALF) between Stockholm County Council and Karolinska Institutet
Address [1] 293334 0
Stockholm County Council Stockholms lans landsting Box 22550 104 22 Stockholm
Country [1] 293334 0
Primary sponsor type
Prof Olav Rooyackers
Karolinska Institutet
Inst. for klinisk vetenskap, intervention och teknik
Enheten for anestesi
Karolinska Universitetssjukhuset, Huddinge, K32
141 86 Stockholm
Secondary sponsor category [1] 292153 0
Name [1] 292153 0
Address [1] 292153 0
Country [1] 292153 0

Ethics approval
Ethics application status
Ethics committee name [1] 294803 0
Regionala etikprovningsnamnden i Stockholm
Ethics committee address [1] 294803 0
Box 289 (Nobels vag 12 A) 171 77 Stockholm
Ethics committee country [1] 294803 0
Date submitted for ethics approval [1] 294803 0
Approval date [1] 294803 0
Ethics approval number [1] 294803 0

Brief summary
We are using a method to measure the contribution from enteral feeding to whole-body protein turnover in critically ill patients, using stable-isotope-labeled phenylalanine tracers. One underlying assumption is that, during continuous feeding, nutrients and tracers reach a steady state of uptake and distribution. Unpublished data from a pilot study in n=10 ICU patients show that this assumption may not always be tenable. We therefore plan to investigate in healthy subjects whether a continuous infusion of 13C-phenylalanine results in a steady state of 13C-phenylalanine enrichment in plasma. N=10 healthy subjects are given a continuous infusion of nutrition formula for a a total of 24 hrs. After an equilibration phase of 12 hrs a 13C-phenylalanine tracer is added to the infusion for the remaining 12 hrs. Blood samples are taken every 30 minutes during tracer infusion and plasma enrichment of 13C-phenylalanine is measured by gas chromatogrphy-mass spectrometry. The time course of 13C-Phe enrichment is analysed to detect deviation from steady-state conditions.
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 53742 0
Prof Olav Rooyackers
Address 53742 0
Karolinska Institutet Inst. for klinisk vetenskap, intervention och teknik Enheten for anestesi Karolinska Universitetssjukhuset, Huddinge, K32 141 86 Stockholm
Country 53742 0
Phone 53742 0
Fax 53742 0
Email 53742 0
Contact person for public queries
Name 53743 0
Prof Olav Rooyackers
Address 53743 0
Karolinska Institutet Inst. for klinisk vetenskap, intervention och teknik Enheten for anestesi Karolinska Universitetssjukhuset, Huddinge, K32 141 86 Stockholm
Country 53743 0
Phone 53743 0
Fax 53743 0
Email 53743 0
Contact person for scientific queries
Name 53744 0
Prof Olav Rooyackers
Address 53744 0
Inst. for klinisk vetenskap, intervention och teknik Enheten for anestesi Karolinska Universitetssjukhuset, Huddinge, K32 141 86 Stockholm
Country 53744 0
Phone 53744 0
Fax 53744 0
Email 53744 0

No information has been provided regarding IPD availability
Summary results
No Results