关于密度检查的几个问题

如何看骨密度检测的结果？

随着老龄化社会到来以及对于骨质疏松性骨折危害的认识，越来越多的医生和患者开始重视抗骨质疏松的治疗，但是合适开始治疗，治疗的效果如何评价？骨密度检测便成了目前最为常用的手段，很多人拿到结果来咨询，同时对于检测的次数和放射线有疑虑，查阅了相关的文章和维基百科，就3个大家最为关心的问题进行了简单总结，供大家参考：

1、BMD的结果是和两个标准比较得来的，T值是和25岁（也有文献为30岁）同性别健康成人匹配对比的结果，Z值是和同龄人匹配对比的结果，因此其曲线更像生长曲线。

2、DXA安全吗？

DXA是很安全的，放射的剂量相当于夏天在户外一天晒太阳，或者乘坐飞机飞越美国，是拍一次胸片的十分之一。

3、多久进行一次BMD合适？

成人一年不超过一次，BMD的变化较缓慢，在开始一项新的治疗前和半年到1年后进行BMD检测是合适的。

Results are generally scored by two measures, theT-scoreand theZ-score. Scores indicate the amount one's bone mineral density varies from the mean. Negative scores indicate lower bone density, and positive scores indicate higher.

The T-score is the relevant measure when screening for osteoporosis. It is the bone mineral density (BMD) at the site when compared to theyoung normal reference mean. It is a comparison of a patient's BMD to that of a healthy 30-year-old. The US standard is to use data for a 30-year-old of the same sex and ethnicity, but the WHO recommends using data for a 30-year-old white female for everyone.[7]Values for 30-year-olds are used in post-menopausal women and men over age 50 because they better predict risk of future fracture.[8]The criteria of theWorld Health Organizationare:[9]

Normal is a T-score of −1.0 or higher

Osteopeniais defined as between −1.0 and −2.5

Osteoporosisis defined as −2.5 or lower, meaning a bone density that is two and a half standard deviations below the mean of a 30-year-old man/woman.

The Z-score is the comparison to theage-matched normaland is usually used in cases of severe osteoporosis. This is the number of standard deviations a patient's BMD differs from the average BMD of their age, sex, and ethnicity. This value is used in premenopausal women, men under the age of 50, and in children.[8]It is most useful when the score is less than 2 standard deviations below this normal. In this setting, it is helpful to scrutinize for coexisting illnesses or treatments that may contribute to osteoporosis such as glucocorticoid therapy, hyperparathyroidism, or alcoholism.