Morning specimen is not representative of metabolic control in Tunisian children with phenylketonuria: a repeated cross-sectional study

Rim Ben Abdelaziz; Nizar Tangour; Amel Ben Chehida; Sameh Haj Taieb; Moncef Feki; Hatem Azzouz; Neji Tebib

doi:10.1515/jpem-2020-0025

Article

Morning specimen is not representative of metabolic control in Tunisian children with phenylketonuria: a repeated cross-sectional study

Rim Ben Abdelaziz , Nizar Tangour , Amel Ben Chehida , Sameh Haj Taieb , Moncef Feki , Hatem Azzouz and Neji Tebib

Published/Copyright: July 12, 2020

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From the journal Journal of Pediatric Endocrinology and Metabolism Volume 33 Issue 8

Abstract

Objective and methods

To evaluate variation of capillary phenylalanine concentrations over the day in patients treated for phenylketonuria and the reliability of the morning sample to assess metabolic control, we conducted a repeated cross-sectional study in 25 Tunisian patients on phenylalanine-low diet. For each patient, we collected nine capillary samples over the day. Phenylalanine was dosed by fluorimetry.

Results

There was a wide variability of phenylalanine concentrations over the day (p<0.001). Compared to morning sample, phenylalanine concentration was significantly lower before lunch (p=0.038), after lunch (p=0.025), before dinner (p<0.001), after dinner (p=0.035) and at 4:00 a.m. (p=0.011). Compared to the 24 h sampling, the morning sample had a 68% to identify unbalanced patients. 60% of patients, had peak phenylalanine concentration after the morning. Half of the patients with normal morning phenylalanine concentration had low phenylalanine values over 8–20 h. Percentages of high phenylalanine concentrations over the last semester were higher in patients with poor metabolic control over the 24 h (21% ± 43 vs. 0% ± 9%); p=0.043.

Conclusion

A single morning sample gives an incomplete information on metabolic control in phenylketonuric patients. Using four pre-prandial samples on the day should be considered as alternative in patients with good metabolic control.

Keywords: concentration; follow-up; monitoring; phenylalanine-low diet; phenylalanine; variation

Corresponding author: Rim Ben Abdelaziz, Department of Pediatrics, La Rabta Hospital, Jabbari, 1007, Tunis, Tunisia; Faculty of Medicine of Tunis, University of Tunis Elmanar, Tunis, Tunisia; and Research Laboratory LR12SPO2, Ministry of High Education, Tunis, Tunisia, E-mail: rimelair@gmail.com, rimbenabdelaziz@yahoo.fr

Acknowledgements

We wish to thank the participating families.

Research funding: None declared.
Author contribution: RBA: conceptualization, methodology, formal analysis, investigation, resources, data curation, writing original draft and project administration. NT: investigation, data curation and writing original draft. ABC: conceptualization, resources, review and editing. SHT: investigation, data curation. MF: investigation, data curation. HA: resources, review and editing. NT: resources, supervision
Competing interests: Authors state no conflict of interest.
Informed consent: Informed consent was obtained from all individuals included in this study.

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Received: 2020-01-27

Accepted: 2020-05-04

Published Online: 2020-07-12

Published in Print: 2020-08-27

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Articles in the same Issue

https://doi.org/10.1515/jpem-2020-0025

Keywords for this article

concentration; follow-up; monitoring; phenylalanine-low diet; phenylalanine; variation