Background Accurate measurement of phenylalanine (Phe) is a requirement for the diagnosis and management of individuals with Phenylketonuria (PKU). The current methods for quantifying Phe, plasma amino acids, and dried blood spots (DBS) have several analytical limitations and are not suitable for self-monitoring. This study evaluated the validity of a point-of-care testing (POCT) device, the Egoo Phe Test, in a sample of females with PKU who participated in a five-day camp intervention. Methods Blood samples were collected from 20 participants (median age: 18 years; IQR: 16, 28.3) on the first (day 1) and/or final (day 5) day of camp for Phe quantification by plasma amino acids, DBS, and the Egoo Phe Test. Phe concentrations determined by these three methods were compared to assess agreement. Results On both days of camp, strong positive agreement based on Lin’s concordance correlation coefficient (pc) was found between Egoo and DBS (day 1: pc = 0.91 [95% CI: 0.78, 0.96]; day 5: pc = 0.91 [95% CI: 0.79, 0.96]) and moderate positive agreement was identified between Egoo and plasma amino acids (day 1 pc = 0.80 [95% CI: 0.63, 0.89]; day 5 pc = 0.83 [95% CI: 0.68, 0.91]). Phe concentrations measured by the Egoo were lower than Phe concentrations determined by plasma amino acids (day 1 average difference: -31.2% [95% CI: − 40.2, − 25.8]; day 5 average difference: -12.4% [95% CI: -30.4, − 4.2]) and higher than DBS (day 1 average difference: 16.2% [95% CI: 4.6, 25.3]; day 5 average difference: 12.2% [95% CI: − 1.4, 20.5]). When assessing pairwise differences between the methods for each sample, > 66.7% of the Egoo Phe results were within ± 20% difference of the DBS values on day 5 of camp. However, this criterion was not met when comparing Egoo with DBS on day 1 of camp or with plasma amino acids on either day of camp. Conclusions The Egoo Phe Test demonstrated potential as a substitute for DBS, but additional research in larger and more diverse clinical cohorts is required. Future research should focus on improving accuracy and defining analytical targets that consider the clinical impact of Phe test performance on management of patients with PKU. Clinical trial number: not applicable.

Performance of the Egoo test for phenylalanine measurement in females with phenylketonuria

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2025年10月10日

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Meriah S. Schoen,
Serei Vatana Nath,
Rani H. Singh

摘要

Background

Accurate measurement of phenylalanine (Phe) is a requirement for the diagnosis and management of individuals with Phenylketonuria (PKU). The current methods for quantifying Phe, plasma amino acids, and dried blood spots (DBS) have several analytical limitations and are not suitable for self-monitoring. This study evaluated the validity of a point-of-care testing (POCT) device, the Egoo Phe Test, in a sample of females with PKU who participated in a five-day camp intervention.

Methods

Blood samples were collected from 20 participants (median age: 18 years; IQR: 16, 28.3) on the first (day 1) and/or final (day 5) day of camp for Phe quantification by plasma amino acids, DBS, and the Egoo Phe Test. Phe concentrations determined by these three methods were compared to assess agreement.

Results

On both days of camp, strong positive agreement based on Lin’s concordance correlation coefficient (p_c) was found between Egoo and DBS (day 1: p_c = 0.91 [95% CI: 0.78, 0.96]; day 5: p_c = 0.91 [95% CI: 0.79, 0.96]) and moderate positive agreement was identified between Egoo and plasma amino acids (day 1 p_c = 0.80 [95% CI: 0.63, 0.89]; day 5 p_c = 0.83 [95% CI: 0.68, 0.91]). Phe concentrations measured by the Egoo were lower than Phe concentrations determined by plasma amino acids (day 1 average difference: -31.2% [95% CI: − 40.2, − 25.8]; day 5 average difference: -12.4% [95% CI: -30.4, − 4.2]) and higher than DBS (day 1 average difference: 16.2% [95% CI: 4.6, 25.3]; day 5 average difference: 12.2% [95% CI: − 1.4, 20.5]). When assessing pairwise differences between the methods for each sample, > 66.7% of the Egoo Phe results were within ± 20% difference of the DBS values on day 5 of camp. However, this criterion was not met when comparing Egoo with DBS on day 1 of camp or with plasma amino acids on either day of camp.

Conclusions

The Egoo Phe Test demonstrated potential as a substitute for DBS, but additional research in larger and more diverse clinical cohorts is required. Future research should focus on improving accuracy and defining analytical targets that consider the clinical impact of Phe test performance on management of patients with PKU.

Clinical trial number:

not applicable.