## Table 4 |
||||||

Correlation of phenylalanine and tyrosine concentrations and phenylalanine: tyrosine
concentration ratio between different types of samples |
||||||

Real time |
Delay 1 h |
Delay 2 h |
||||

Variable |
r |
p |
r |
p |
r |
p |

Correlation between serum and dried blood |
||||||

Phe | .50 | .01 | ||||

Tyr | .96 | < .001 | ||||

[Phe]/[Tyr] | .96 | < .001 | ||||

Correlation between serum and microdialysate |
||||||

Phe | -.11 | .64 | -.15 | .48 | -.24 | .25 |

Tyr | .54 | .01 | .23 | .28 | .04 | .84 |

[Phe]/[Tyr] | .76 | < .001 | .52 | .01 | .28 | .18 |

Phe = phenylalanine; Tyr = tyrosine; [Phe]/[Tyr] = phenylalanine: tyrosine concentration ratio.

The correlation analysis of phenylalanine and tyrosine concentrations and of the phenylalanine:
tyrosine concentration ratio ([Phe]/[Tyr]) between microdialysis fluid and serum was
performed with samples taken simultaneously (“Real time”) and with microdialysate
samples taken one hour (“Delay 1 h”) and two hours (“Delay 2 h”) after blood sampling.
To assess the above-mentioned correlations Pearson’s correlation coefficients (*r*) were calculated for each patient, then transformed to Fisher-*Z* values (Fisher r-to-Z transformation) and averaged. Resulting mean Fisher-Z values
were retransformed to *r* values (reversed Fisher transformation).

Grünert * et al.*

Grünert * et al.* *Nutrition Journal* 2013 **12**:60 doi:10.1186/1475-2891-12-60