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Table 6 High blood phenylalanine levels and suggested actions

From: PKU dietary handbook to accompany PKU guidelines

Cause of high blood phenylalanine levels Action
Fever/infection/trauma See section on illness management
Excess natural protein intake • Check understanding/calculation of phenylalanine allowance/ exchanges, misinterpretation/misunderstandings of protein amounts in foods. Review portion sizes.
• Check any intentional dietary non-adherence (e.g. patient chose to eat extra protein).
• Check any special low protein products are low protein and not gluten-free by accident.
• Re-educate patient or family if necessary.
Inadequate intake of protein substitute • Check adherence (at home, nursery, school). Explore any reasons for poor adherence and either re-educate or change type or flavour of protein substitute if appropriate.
• Check timing of protein substitute (should be spread throughout the day).
• Check patient has adequate supply of protein substitute.
• Re-calculate dose of protein substitute and increase the dosage if necessary.
Incorrect prescription of protein substitute • Occasionally the wrong protein substitute may accidentally be prescribed or given by the pharmacist or a home delivery company.
Low energy intake/weight loss/catabolism • Increase energy intake/give extra carbohydrate. Encourage extra low protein foods or high calorie drinks.
No obvious reason • If blood phenylalanine levels are consistently high, consider a reduction in natural protein/phenylalanine by approx. 0.5 to 1 g/day protein or 25 to 50 mg phenylalanine/day.
  1. Table adapted from MacDonald A, White F. Amino acid disorders. In Shaw V, editor. Clinical Paediatric Dietetics: Chichester: Wiley Blackwell; 2015. p. 433