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The Z-score for bone density is the comparison to the "age-matched normal" and is usually used in cases of severe osteoporosis. This is the standard score or number of standard deviations a patient's bone mineral density differs from the average for their age, sex, and ethnicity. This value is used in premenopausal women, men under the age of ...
Bone densities are often given to patients as a T score or a Z score. A T score tells the patient what their bone mineral density is in comparison to a young adult of the same gender with peak bone mineral density. A normal T score is -1.0 and above, low bone density is between -1.0 and -2.5, and osteoporosis is -2.5 and lower.
Quantitative computed tomography (QCT) differs from DXA in that it gives separate estimates of BMD for trabecular and cortical bone and reports precise volumetric mineral density in mg/cm 3 rather than BMD's relative Z-score. Among QCT's advantages: it can be performed at axial and peripheral sites, can be calculated from existing CT scans ...
The trabecular bone has much higher metabolic activity than the cortical bone and so is affected by age, disease and therapy-related changes earlier and to a greater degree than cortical bone. This means that QCT of the spine has an advantage compared to other bone density tests because earlier changes in bone mineral density may be detected . [1]
In educational assessment, T-score is a standard score Z shifted and scaled to have a mean of 50 and a standard deviation of 10. [14] [15] [16] In bone density measurements, the T-score is the standard score of the measurement compared to the population of healthy 30-year-old adults, and has the usual mean of 0 and standard deviation of 1. [17]
The trabecular bone score is a measure of bone texture correlated with bone microarchitecture and a marker for the risk of osteoporosis. Introduced in 2008, [ 1 ] its main projected use is alongside measures of bone density in better predicting fracture risk in people with metabolic bone problems.
Z tables use at least three different conventions: Cumulative from mean gives a probability that a statistic is between 0 (mean) and Z. Example: Prob(0 ≤ Z ≤ 0.69) = 0.2549. Cumulative gives a probability that a statistic is less than Z. This equates to the area of the distribution below Z. Example: Prob(Z ≤ 0.69) = 0.7549. Complementary ...
Information from the DXA scanner creates a bone mineral density T-score by comparing a patient's density to the bone density of a healthy young person. Bone density between 1 and 2.5 standard deviations below the reference, or a T-score between −1.0 and −2.5, indicates osteopenia (a T-score smaller than or equal to −2.5 indicates ...