Weaning practices in phenylketonuria vary between health professionals in Europe

Abstract

BackgroundIn phenylketonuria (PKU), weaning is considered more challenging when compared to feeding healthy infants. The primary aim of weaning is to gradually replace natural protein from breast milk or standard infant formula with solids containing equivalent phenylalanine (Phe). In addition, a Phe-free second stage L-amino acid supplement is usually recommended from around 6 months to replace Phe-free infant formula. Our aim was to assess different weaning approaches used by health professionals across Europe.MethodsA cross sectional questionnaire (survey monkey®) composed of 31 multiple and single choice questions was sent to European colleagues caring for inherited metabolic disorders (IMD). Centres were grouped into geographical regions for analysis.ResultsWeaning started at 17–26 weeks in 85% (n = 81/95) of centres, >26 weeks in 12% (n = 11/95) and < 17 weeks in 3% (n = 3/95). Infant's showing an interest in solid foods, and their age, were important determinant factors influencing weaning commencement. 51% (n = 48/95) of centres introduced Phe containing foods at 17–26 weeks and 48% (n = 46/95) at >26 weeks. First solids were mainly low Phe vegetables (59%, n = 56/95) and fruit (34%, n = 32/95).A Phe exchange system to allocate dietary Phe was used by 52% (n = 49/95) of centres predominantly from Northern and Southern Europe and 48% (n = 46/95) calculated most Phe containing food sources (all centres in Eastern Europe and the majority from Germany and Austria). Some centres used a combination of both methods.A second stage Phe-free L-amino acid supplement containing a higher protein equivalent was introduced by 41% (n = 39/95) of centres at infant age 26–36 weeks (mainly from Germany, Austria, Northern and Eastern Europe) and 37% (n = 35/95) at infant age > 1y mainly from Southern Europe. 53% (n = 50/95) of centres recommended a second stage Phe-free L-amino acid supplement in a spoonable or semi-solid form.ConclusionsWeaning strategies vary throughout European PKU centres. There is evidence to suggest that different infant weaning strategies may influence longer term adherence to the PKU diet or acceptance of Phe-free L-amino acid supplements; rendering prospective long-term studies important. It is essential to identify an effective weaning strategy that reduces caregiver burden but is associated with acceptable dietary adherence and optimal infant feeding development.

PKU dietary handbook to accompany PKU guidelines

“…There is evidence to suggest that some individuals with PKU may tolerate more phenylalanine than they have been prescribed by their health professionals [8][9][10]. The only way that this can be tested is to systematically challenge individuals with additional phenylalanine.…”

“…Most PKU centres introduce solids from between 17 to 26 weeks of age which is a little earlier than the recommendation of 26 weeks for the general population [9]. In PKU, weaning development is similar to non PKU infants.…”

“…From the age of 6 months, it becomes necessary to introduce a more concentrated protein substitute or second stage protein substitute. This is common practice in Europe [9]. The amount of second stage protein substitute is gradually increased in order to meet total protein requirements.…”

Uniformity of Food Protein Interpretation Amongst Dietitians for Patients with Phenylketonuria (PKU): 2020 UK National Consensus Statements

“…It is acknowledged that internationally, different systems are used to calculate/measure protein/phenylalanine in the PKU diet, each with its own inherent weaknesses [4][5][6][7][8][9]. Using upper protein/phenylalanine cut-off points has the disadvantage of having to measure/calculate foods as part of an exchange system if they contain protein marginally over the cut-off, whilst eating foods as exchange-free if they are just under the cut-off point, but it does give direct guidance and allows many foods to be eaten without measurement or calculation.…”

“…Whilst the goal of dietetic management is essentially the same, the method for allocating phenylalanine/protein intake varies between and sometimes within countries, with insufficient evidence to recommend any one method [4][5][6][7][8][9]. Broadly there are two different methods, each with its merits and drawbacks: (1) patients are allocated a daily amount of phenylalanine/protein from all food, which is calculated to provide the prescribed phenylalanine intake; and (2) a phenylalanine/protein exchange system whereby amounts of food are calculated for a defined amount of phenylalanine (ranging from 10-50 mg of phenylalanine for each exchange) or protein (e.g., 1 g protein = 1 exchange).…”