Background: Lumbar spine and total hip are widely used to measure bone mineral density (BMD) for diagnosis of osteoporosis. We want to evaluate relationship and concordance of the osteoporotic diagnosis between lumbar spine and total hip BMD in post-menopausal women.

Methods: The BMD on both hips and lumbar spine of 100 healthy post-menopausal women were measured using dual-energy X-ray absorptiometry (DEXA). The BMDs of total hip and lumbar 1~4 were classified into normal (T-score＞?1.0), osteopenia (?1.0≥T-score＞?2.5), osteoporosis (T-score≤?2.5) using WHO definitions.

Results: Based on L1~4 T-score there were 15 osteoporotic, 35 ostepenic, 50 normal persons, and based on total hip T-score there were 1 osteoporotic, 20 ostepenic, 79 normal persons. There was significant correlation between total hip and lumbar BMDs (r=0.695). For all age groups, lumbar BMDs are lower than hip BMDs and the gaps are severe in older group. The discordance rate was 43% for all cases, and this was 36% in their 50’s, 65% in 60’s, and 60% in 70’s with the highest rate in 60’s (P＜0.05). The discordance rates of the normal, osteopenic and osteoporotic groups were 39, 60 and 0% respectively, with the highest rate in osteopenic group (P＜0.05).

Conclusion: The discordance rate between total hip and lumbar spine was as high as 43%, and was the highest in the osteopenic group in their 60’s. Therefore in post-menopausal women, the BMD of both sites should be checked together, but if not, the lumbar BMD should be checked first.