Bone metabolism in adults with phenylketonuria - Hungarian data

Abstract

Patients with phenylketonuria have lower bone mineral density compared to healthy people, however, the ethiology of these alterations is not clear. Hungarian data were missing in this topic. The main aim of our study was to survey the correlation between metabolic control and change of bone mineral density in early treated Hungarian adult patients with phenylketonuria. In this monocentric study bone mineral density of 59 adult PKU patients have been repeatedly measured in a 4-year interval using dual-energy X-ray absorptiometry. Two subgroups have been established based on average blood phenylalanine levels. The correlation between the change in bone mineral density and average phenylalanine, tyrosine concentrations have been determined while initial bone mineral density and change have also been examined in the subgroups. Mean phenylalanine concentration was 614 (182-1222) micromol/L, whereas mean tyrosine concentration was 49 (24-99) micromol/L and the calculated ratio was 16 (4,5-35). Three patients have had severely decreased bone mineral density in either localisation while 22 have had mild decrease. Low bone mineral density compared to cronological age has been found by 9 patient. The mean change was +0.0380 (-0.1550-0.7800) g/cm2 in femur, and +0.0120 (-0.57300-0.3130) g/cm2 in the lumbar spine. There was a correlation in the change in Z-score neither with mean phenylalanine nor with tyrosine concentration. Bone mineral density was not changed and hardly influenced by the metabolic control in early-treated young adult phenylketonuria patients in a few years interval. Orv Hetil. 2017; 158(47): 1868-1872.