Sex and age specific bone mineral density trends in Sri Lankan adults support the need for normative reference data

Introduction: Bone Mineral Density (BMD) is a critical determinant of osteoporosis diagnosis and fracture risk. Absence of normative BMD data for Sri Lankans has necessitated reliance on Caucasian references, potentially misestimating the BMD. This study aimed to establish age-related BMD trends for optimal bone health management. Methods: A retrospective correlational analysis was conducted on 10,946 adults (4,005 men, 6,941 women; 21-80 years) who underwent lumbar spine and hip scans using Hologic Dual Energy X-ray absorptiometry at five private health institutions in Western Province. Individuals with medical conditions or treatments known to affect bone metabolism were excluded. Results: BMD values showed strong positive correlations across lumbar spine and hips (r = 0.61 - 0.94, p < 0.001) with negligible bias between hips (mean difference ≈ 0.003 g/cm2). Minor right - left hip differences appeared only in 21- 30 age group (p < 0.05). Males had consistently higher BMD than females. In females, lumbar BMD peaked at 31-40 years (0.980 g/cm2) and declined thereafter (F = 279.76, p < 0.001; η² = 0.156); hip BMD peaked at 41-50 years (~0.95 g/cm2) and declined after 50 years (~0.04-0.06 g/cm2 /decade). In males, lumbar BMD peaked at 31-40 years (0.997 g/cm2) with modest decline (F = 4.73, p < 0.001; η² = 0.006), while hip BMD remained stable until 60, then decreased (~0.03 g/cm2 /decade). Contralateral hip BMD showed strong symmetry, supporting the reliability of single-hip measurements in clinical practice. Higher body mass index was positively associated with BMD in both sexes, particularly in women. Years since menopause accounted for a substantial portion of variance (15%-19%) in BMD, with trabecular-rich lumbar spine exhibiting faster early loss compared to cortical-rich hips, which declined more gradually in later decades. Compared with Caucasian reference data, Sri Lankan participants displayed consistently lower BMD, with the greatest deficits observed in postmenopausal women (up to 15% lower), highlighting the need for population-specific reference ranges. Discussion: These findings demonstrate the need for population-specific BMD reference values to improve diagnostic accuracy and guide clinical management of osteoporosis and osteopenia, particularly in postmenopausal women and older adults.