Skip to main content

Table 3 Blood Phe levels in treating and monitoring children with PAH deficiency

From: Nutritional management of phenylalanine hydroxylase (PAH) deficiency in pediatric patients in Canada: a survey of dietitians’ current practices

  n (%)
Blood Phe level (consistently elevated) to prompt initiation of a Phe-restricted diet (n = 19)
  ≥ 360 μmol/L (≥6 mg/dL) 14 (74)
 360–420 μmol/L (6–7 mg/dL) 1 (5)
  ≥ 420 μmol/L (≥7 mg/dL) 1 (5)
  ≥ 480 μmol/L (≥8 mg/dL) 2 (10)
  ≥ 600 μmol/L (≥10 mg/dL) 1 (5)
Optimal target range of blood Phe, by age
 0–12 months of age (n = 19)
  120–360 μmol/L (2–6 mg/dL) 19 (100)
  > 1–2 years of age (n = 19)
  120–360 μmol/L (2–6 mg/dL) 19 (100)
  > 2–10 years of age (n = 19)
  120–360 μmol/L (2–6 mg/dL) 19 (100)
  > 10–18 years of age (n = 18)
  120–360 μmol/L (2–6 mg/dL) 14 (78)
  120–600 μmol/L (2–10 mg/dL) 2 (11)
  320–600 μmol/L (5.33–10 mg/dL) 2 (11)
Lowest acceptable average level of blood Phe as a long-term treatment goal, by age
 0–12 months of age (n = 18)
  100 μmol/L 1 (6)
  120 μmol/L 17 (94)
  > 1–2 years of age (n = 17)
  120 μmol/L 16 (94)
  150 μmol/L 1 (6)
  > 2–10 years of age (n = 17)
  120 μmol/L 16 (94)
  150 μmol/L 1 (6)
  > 10–18 years of age (n = 18)
  100 μmol/L 1 (6)
  120 μmol/L 16 (89)
  200 μmol/L 1 (6)
Would you be comfortable with a patient’s steady Phe level of < 120 μmol/L (n = 19)
 Yes 6 (32) a
 No 13(68)
Recommend maintaining higher-end therapeutic range blood Phe and more liberal natural protein intake (n = 19)
 For most/nearly all patients 5 (26)
 For some patients 9 (47)
 Rarely/never 5 (26)
Recommend maintaining lower-end therapeutic range blood Phe levels and more restricted natural protein intake (n = 19)
 For most/nearly all patients 4 (21)
 For some patients 4 (21)
 Rarely/never 11 (58)
  1. aIf yes, participants were asked to explain – open-ended responses: “If levels were consistent and testing was done weekly, I would be ok it with somewhat lower levels, perhaps as low as 80; I would be more comfortable with an older child (> 2 years), but this rarely happens; On Kuvan & hard to increase Phe intake; On restricted diet but growing well; I would be comfortable with <120umol/L in maternal PKU where I was certain formula and calorie intake was optimized and the patient was careful with foods they chose to ensure good nutrition; If patients are experiencing rapid growth (usually in infancy); Only for super responders to Kuvan tolerating DRI total protein from regular protein foods with minimal or no PKU foods”