Childhood reference range based on the age is not available in Hungary, therefore the diagnosis and therapy of bone metabolic diseases of childhood are subject to difficulties. The aim of this work is to provide information about the adolescents' results of bone mineral density and bone biomarkers.
Subjects and methods: Measurements were performed in 169 healthy adolescents (98 girls, 71 boys, age: 17.0+/-1.2 years). Bone mineral content (BMC) and bone mineral density (BMD) of the lumbar spine were measured using Double X-ray Absorptiometry (DXA, LUNAR, GE Health Care, USA) and Z-score values were analyzed using different reference population. In the serum, bone biomarkers osteocalcin (OC) and beta-crosslaps (beta-Cl) were measured by a fully automated, electrochemiluminescence immunoassay method (Elecsys-2010, Roche). Data were analyzed according to gender and the Tanner stage and grade system. Associations between body mass index (BMI), calcium intake, consumption of soft drinks and coke, and physical exercise were investigated.
Results: BMC values for both age groups were significantly elevated in boys of the Tanner stage V. (15-16 years: 62.9+/-14.3 g; 17-19 years: 69.8+/-9.3g) than in girls (58.1+/-10.4; 61.6+/-8.5 g) (p<0.001). BMD values were higher in girls, than in boys (1.17+/-0.12 g/cm 2 vs. 1.13+/-0.11 g/cm 2) (p<0.05). OC and beta-Cl levels showed negative correlation with age in both gender (p<0.01), while OC and beta-Cl levels were higher in boys, than in girls (p<0.001). Elevation of BMC and BMD values were associated with increase of BMI in both gender (p<0.05), but the biomarkers in thin girls were higher, than in overweight girls (p<0.05). Authors obtained excellent correlations between the BMD-Z-score values compared to the German standard and to their own population (girls: r=0.97, boys: 0.88), but the absolute values significantly differed from one another. 80% of adolescents are on a diet with insufficient calcium intake, while 38% of them do not play sport regularly. Excessive intake of soft drinks was determined in 60% of adolescents. In the case of insufficient calcium intake (4.7%, 6/127), low bone mass was measured using the Z-score of the German reference values. Among children with adequate calcium intake, BMD assessed by DXA was normal.
Conclusion: These data help to determine normal reference values among healthy high school students. Further studies are needed in wider range of young population for the establishment of Hungarian reference values of bone markers.