Bone development in children and adolescents with PKU.

INTRODUCTION

Individuals with phenylketonuria (PKU, OMIM 261600) have shown bone disease from childhood. Factors such as non-adherence to treatment, nutritional inadequacy, and high phenylalanine levels are associated with bone disease in several studies. This research aimed to describe the impact of dietary factors (consumption of energy, protein, calcium, phosphorus, and phenylalanine), and the control of plasma phenylalanine levels on bone age (BA) and bone mineral density (BMD).

METHODOLOGY

Thirteen patients of both genders, from 8 to 16 years old participated in this study. Control data were collected of phenylalanine levels, food frequency and record, hand and fist X-rays, and spinal bone densitometry.

RESULTS

In children group (CG), individuals non-adherent to diet (NAD) consumed lower amounts of calcium (472 ± 100 mg/day) and energy (1743 ± 486 Kcal); they had higher rates of phenylalanine (564 ± 94 μmol/L) in blood, intake phenylalanine (701 ± 334 mg/g), and higher protein intake from free foods (14 ± 6.67 g/day); bone age (BA) values higher than the chronological age (CA) and less BMD values (-0.7 ± 1.6 SD) also were verified. In adolescent group (AG, N = 8) of NAD, values were lower for energy intake (1379 ± 258 Kcal), calcium (801 ± 152 mg/day), phosphorus (657 ± 102 mg/day), food protein (25 ± 7.6 g/day), and intake phenylalanine (1067 ± 382 mg/day) than recommended. Higher levels of plasma phenylalanine (851 ± 244 μmol/L), bone age greater than chronological age and lower BMD values (-2.4 ± -2.5 SD) were observed.

CONCLUSION

The results suggest effects on BA and on BMD, in both children and adolescent groups. The bone development is expressed differently in children and adolescents. The non-adherence to the diet verified in both groups and the consequent imbalance in the nutrients intake involved in bone metabolism suggest that these factors influence the failure to thrive in children and reduced bone mineralization in adolescents.