What tests may be used to determine blood levels of Phe?
=> The Guthrie test is most commonly used. One may also use HPLC. There is also a fluorometric method. An older, simple but inaccurate method depends on the formation of a blue-green complex of urinary phenylpyruvate with ferric ion (from a ferric chloride solutions.) This method is inaccurate because other compounds in the urine may also form colored complexes and mask the color of the ferric-pyruvate complex.
