Table 7 Low blood phenylalanine levels and action that should be taken
Cause of low blood phenylalanine levels | Action |
|---|---|
Inadequate intake of natural protein | • Ensure all prescribed intake of natural protein/phenylalanine is eaten. • Check understanding of exchange system/phenylalanine content of foods. • Re-educate as necessary. |
Anabolic phase, following an intercurrent infection | • Ensure all prescribed intake of natural protein is eaten. • Repeat blood phenylalanine level, and if is still low, consider an increase of natural protein by approx. 0.5-1 g protein or 25 to 50 mg/day phenylalanine but monitor blood phenylalanine levels carefully. |
Rapid growth spurt such as puberty | • Increase natural protein by 0.5-1 g/day protein or phenylalanine by 25 to 50 mg/day if blood phenylalanine levels are consistently below target range. • Increase by a further 0.5 to 1 g/day protein or phenylalanine by 25 to 50 mg/day for every 3 consecutive blood phenylalanine levels below target range. |
Excess intake of infant protein substitute or overnight consumption of infant protein substitute. | • Infants may take phenylalanine- free infant protein substitute overnight, which may lower morning blood concentrations. Consider reducing overnight intake if appropriate. |
No obvious reason | • Consider increasing natural protein by approx. 0.5-1 g protein or phenylalanine by 25 to 50 mg/day. • Monitor blood phenylalanine levels carefully. • It is good practice to re-check blood phenylalanine levels before any further increase in natural protein /phenylalanine intake. |