Anthropometric characteristics and nutrition in a cohort of PAH-deficient patients

Summary Background & aims Treating phenylketonuria based upon strict vegetarian diets has occasionally been found to hamper physical development, some patients presenting with growth retardation and malnutrition. In addition, some researchers have reported an association between higher protein intakes and attaining better developmental outcomes, although it remains unclear which protein fraction (natural or synthetic) has the greatest influence on growth. The present study aimed to evaluate anthropometric characteristics and nutrition in a cohort of patients with phenylketonuria and mild-hyperphenylalaninaemia from birth to adulthood. Methods We conducted a retrospective longitudinal study comparing anthropometric characteristics (weight, height, body mass index, and growth rate) in our patients and healthy subjects, with the measurements expressed as z -scores. Nutritional issues were also considered. Data were collected every 6 months from birth to 18 years of age. Results Growth impairment was observed in phenylketonuric patients. Specifically, there were two well-differentiated periods throughout which height fell well below z -score = 0: from birth to two years of age, and on reaching adulthood. We also found height and weight to be positively correlated with phenylalanine intake. No growth retardation was seen in the patients with mild-hyperphenylalaninaemia. Conclusions Phenylketonuric patients showed growth impairment in the early stages, with higher phenylalanine intakes being associated with attaining better developmental outcomes in this period. Therefore, prescribing very stringent diets in the early years might predispose phenylketonuric patients to retarded growth later in life, with growth outcomes in adulthood being well below the 50th percentile for healthy subjects.