ACQUISITION OF BONE MASS DURING EARLY ADULTHOOD: A PROSPECTIVE COHORT STUDY

Abstract

Since most of our current knowledge about the concept of bone gain during adolescence or early adulthood comes from the cross-sectional studies, we aimed to evaluate natural course of changes in bone mineral density prospectively during early adulthood in a cohort. Twenty-two volunteers (15 female, 7 male) with the mean age of 20.0 ± 0.69 years were enrolled into the study. Subjects with any known secondary cause of osteoporosis were excluded from the study. Demographic variables, anthropometric measurements were recorded. Subjects underwent an interview about risk factors for osteoporosis. Physical activity level and calcium intake were evaluated by European Vertebral Osteoporosis Study questionnaire. Lumbar and femoral bone mineral densities were measured using Dual Energy X-ray Absorptiometry (DXA) at baseline and two years after. L1-4 BMD increased from 0.925 ± 0.099 g/cm2 to 0.957 ± 0.094 g/cm2(p = 0.002) and total femur BMD increased from 0.866 ± 0.113g/cm2 to 0.908 ± 0.108g/cm2(p = 0.0001). BMC of L1-4 increased significantly (p = 0.022), however there was no change in bone area measurements (p = 0.82). In case of femoral total measurements, both BMC and bone area demonstrated significant increase over the study period (p = 0.0001 and p = 0.0001). There were significant positive differences in bone mineral densities for L3, L4 measurements in males and for L3 measurements in females (p = 0.028, p = 0.018 and p = 0.02 respectively). Different from the bone gain during adolescent years which is usually attributed to volumetric expansion of the bones; we were able to demonstrate that bone gain continues through early years of adulthood. It would be rational to extend preventive measures beyond adolescence, into early adulthood to optimize the bone mass.