Table 1 Current classification and treatment guidelines for PAH deficiency

Classical PKU

 > 1200 µmol/L

(> 20 mg/dL)

Yes

Yes

Moderate PKU

900–1200 µmol/L

(15–20 mg/dL)

Yes

Yes

Mild PKU

600–900 µmol/L

(10–15 mg/dL)

Yes

Yes

Mild HPA-gray zone

360–600 µmol/L

(6–10 mg/dL)

Yes (only if < 12 years or in women before/during pregnancy)

Yes^c

PAH deficiency not requiring treatment

120–360 µmol/L

(2–6 mg/dL)

No

No