Table 2 Reference ranges for phenylalanine and tyrosine (µmol/L) during pregnancy by trimester using data adjusted for time from collection

From: Phenylalanine and tyrosine measurements across gestation by tandem mass spectrometer on dried blood spot cards from normal pregnant women

 

First trimester

Second trimester

Third trimester

Phenylalanine

17.9–68.4

22.5–62.9

22.6–57.0

Tyrosine

10.8–59.9

13.6–38.0

13.1–39.2

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