Bone mineral density (BMD) of the hip is routinely measured unilaterally, but can differ between left and right. This study aimed to establish total hip T-score thresholds for measuring contralateral hip BMD, to avoid missing the diagnosis of osteoporosis. In 4914 participants (2709 females) in the Busselton Healthy Ageing Study, BMD of both hips and lumbar spine (L1–L4) was measured by dual-energy x-ray absorptiometry (DXA) using a GE Lunar Prodigy Pro densitometer. Least significant change (LSC) was calculated according to International Society for Clinical Densitometry recommendations. For participants whose left-right total hip BMD difference exceeded LSC, the 95th percentile of the difference in T-score was calculated, then added to −2.5 (the cut-off for osteoporosis) to derive T-score thresholds for measuring contralateral hip to avoid a missed diagnosis in 95% of individuals. Participant mean age (±SD) was 57.4 ± 5.8 years; total hip T-score was 0.7 ± 0.1 in males and −0.2 ± 1.1 in females. Left and right total hip BMD were highly correlated (r = 0.943 for males, 0.959 for females), but in 56.2% of males and 50.0% of females, the left-right difference exceeded the LSC of 0.026 g/cm². In these participants, the 95th percentile of difference in T-score between two hips was 0.872 in males and 0.742 in females. This gave T-score thresholds for measuring contralateral total hip BMD of −1.6 (males) and −1.8 (females). When total hip T-score is between −1.6 and −2.5 (males), or between −1.8 and −2.5 (females), measuring contralateral hip BMD could avoid a missed diagnosis of osteoporosis.

髋关节的骨矿物质密度 (BMD) 通常是单侧测量的，但左右两侧可能不同。本研究旨在建立用于测量对侧髋骨骨密度的全髋 T 值阈值，以避免漏诊骨质疏松症。在巴瑟尔顿健康老龄化研究的 4914 名参与者（2709 名女性）中，使用 GE Lunar Prodigy Pro 密度计通过双能 X 射线吸收测定法 (DXA) 测量了臀部和腰椎(L1–L4) 的 BMD。根据国际临床学会计算最小显着变化（LSC）密度测定建议。对于左右全髋 BMD 差异超过 LSC 的参与者，计算 T 分数差异的第 95 个百分位数，然后加上 -2.5（骨质疏松症的截止值）以得出用于测量对侧髋关节的 T 分数阈值避免 95% 的人漏诊。参与者平均年龄 (±SD) 为 57.4 ± 5.8 岁；男性总髋关节 T 评分为 0.7 ± 0.1，女性为 -0.2 ± 1.1。左右全髋 BMD 高度相关（男性 r = 0.943，女性 r = 0.959），但在 56.2% 的男性和 50.0% 的女性中，左右差异超过了 0.026 g/cm ^{2的 LSC}. 在这些参与者中，两个臀部之间的 T 值差异的第 95 个百分位数在男性中为 0.872，在女性中为 0.742。这给出了测量对侧全髋 BMD 的 T 分数阈值 -1.6（男性）和 -1.8（女性）。当总髋关节 T 值介于 -1.6 和 -2.5（男性）之间，或介于 -1.8 和 -2.5（女性）之间时，测量对侧髋关节 BMD 可以避免漏诊骨质疏松症。