Long-term efficacy of 'ready-to-drink' protein substitute in phenylketonuria.

BACKGROUND

In phenylketonuria (PKU), protein substitute is an essential part of dietary treatment. Short-term studies have demonstrated that liquid protein substitutes (LPS) are efficacious, and improve compliance in teenagers and adults with PKU, although there are no data available to demonstrate that their effectiveness is sustained over time. The present retrospective study aimed to evaluate the long-term efficacy of ready-to-drink protein substitute in a group of people with PKU.

METHODS

Thirty-four patients (17 females and 17 males, median age 14.9 years, range 7.2-53.8 years) with PKU on dietary management were recruited from Birmingham Children's Hospital. All patients who were taking a LPS for a median of 2.4 years (range 6 months to 4.1 years), had their plasma phenylalanine concentrations, anthropometric and nutritional biochemical markers reviewed, both before and when taking the LPS.

RESULTS

There was a significant improvement in median plasma phenylalanine (P < 0.05), vitamin B(12) (P < 0.01), calcium (P < 0.05) and albumin (P < 0.05) concentrations in subjects (n = 13) aged >18 years when taking the LPS. In the children aged 7-18 years (n = 21), median plasma phenylalanine concentrations were maintained on LPS. Their plasma selenium concentrations (P < 0.05) deteriorated, but calcium (P < 0.05), albumin (P < 0.01), haemoglobin (P < 0.01) and haematocrit (P < 0.01) significantly improved.

CONCLUSIONS

This retrospective review suggested that, in adult patients, the long-term use of LPS is associated with better compliance by lowering blood phenylalanine and improving nutritional biochemical markers.