Background

Phenylketonuria (PKU) is the most prevalent disorder caused by an inborn error in aminoacid metabolism, increase in blood phenylalanine concentrations. If untreated, PKU leads to profound and irreversible mental disability.

Objectives

Monitoring children with PKU is permanent challenge for parents and clinicians. Likewise, the laboratory personnel has to provide accurate and eloquent results and very important from a therapeutical point of view, as well. In addition, the laboratory monitoring has to be relatively convenient for the patient and parent in terms of collecting and sending sample to laboratory.

Methods

Monitoring children with PKU is a permanent challenge for parents and clinicians. Likewise, the laboratory personnel has to provide accurate and eloquent results and very important from a therapeutical point of view, as well. In addition, the laboratory monitoring has to be relatively convenient for the patient and parent in terms of collecting and sending sample to laboratory.

Results

The levels of Phe obtained in DBS by both FEIA and LC-MS/MS techniques were lower than those determined in plasma in most cases, the differences recorded increasing proportionally to the concentration values.

The factors influencing the results are represented by the quality of DBS sample and hematocrit value.

Table 1 shows the results which were obtained by the three used techniques.

Table 1.

Conclusion

When the Phe values obtained in DBS by LC-MS/MS or FEIA techniques reach acceptable levels of Phe based on age, it is necessary to check the Phe plasma levels by HPLC.