Diagnostic discrepancies between two closely related forearm bone density measurement sites

Utility and validation of bone mineral density measurements at forearm in predicting trabecular microarchitecture and central-site osteoporosis in aging Indian postmenopausal women-a promising surrogate?

Objective

The objective of this paper was to present the results of our study of the utility of bone mineral density (BMD) measurements at various segments of distal forearm in predicting central-site osteoporosis and deteriorated trabecular microarchitecture.

Methods

This was a cross-sectional study and BMD at the femoral neck, lumbar spine, and distal forearm were assessed using the dual-energy X-ray absorptiometry (DXA) scanner and bone microarchitecture at lumbar spine by trabecular bone score (TBS). The utility of forearm BMD in predicting osteoporosis as well as the deteriorated TBS was assessed by a receiver operating characteristic analysis.

Results

A total of 352 postmenopausal women with mean (SD) age of 60.7 (6.8) years were included. The odds of having osteoporosis at femoral neck [odds ratio (OR) = 14.1, 95% confidence interval (CI): 7.8-25.2] and lumbar spine (OR = 7.5, 95% CI: 4.6-12.1) was highest with the mid-distal radius. A derived T-score cut off ≤ -1.6, -1.9, and -1.7 at any segment of the forearm was elucidated to predict osteoporosis at the central-site, femoral neck, and lumbar spine, respectively, with sensitivity of 80%-88% and specificity of 60%-70%. The T-scores at all three forearm segments ≤ -1.2 showed fair performance in predicting degraded trabecular microarchitecture. The T-scores thus derived were further validated in cohort of 360 Bengali postmenopausal women.

Conclusion

BMD assessment at the forearm may be utilized in prediction of trabecular microarchitecture and central site osteoporosis at the femoral neck and lumbar spine in postmenopausal women.

Forearm bone mineral density measurement with different scanning positions: a study in right-handed Chinese using dual-energy X-ray absorptiometry

The purpose of our study was to determine whether different scanning positions influence forearm bone mineral density (BMD) measurements and to evaluate the association between forearm BMDs in different scanning positions and those of other skeleton sites. The study population consisted of 30 right-handed healthy Chinese volunteers. BMD was measured with GE Lunar Prodigy at the left forearm in both sitting and supine positions, and at lumbar spine and the right femur. All subjects received repeated measurements in the same day (repositioning), and the average of repeated BMD results was used for analysis. The BMD precision errors of the nondominant forearm in the sitting and supine positions varied from 1.13% to 2.46%. There were no statistically significant differences between BMD precision errors for each region of interest (ROI) between sitting and supine positions (all the p values were greater than 0.05). When comparing BMDs on the same side in the sitting position with those in the supine position, there were significant differences at both the 1/3 radius level and in the total radius (p<0.05). The BMD values at these ROIs obtained in the supine position were lower than those in the routine sitting position. The BMDs of the ultradistal radius in the both 2 different scanning positions were significantly associated with lumbar spine and femoral neck BMD, respectively. The total radius BMD in the different positions was associated with the BMD of the femoral neck. A change in body scanning position from sitting to supine will significantly influence forearm BMD results.

Prevalence of low forearm bone mineral density in Bulgarian men: a pilot study

OBJECTIVE

To determine the prevalence of osteoporosis at the distal forearm in a male cohort referred for bone density testing and to compare it to published data of Bulgarian women.

DESIGN AND SUBJECTS

315 consecutive Bulgarian men aged 20 to 84 years were included (mean age 53.74 +/- 14.67 years). 59% of them were self-referrals. The comparative female group consisted of 8869 Bulgarian women whose forearm bone mineral density (BMD) was measured in another study.

MEASUREMENTS

BMD was measured by single X-ray absorptiometry at the distal forearm (distal and ultradistal sites) in all men. T-scores were calculated from manufacturer-provided Danish male reference data.

RESULTS

The ratio of female to male patients was 28.2 (8869 to 315). Peak BMD was observed in men aged 30 to 39 years: 0.560 +/- 0.065 g/cm(2) (distal site) and 0.490 +/- 0.070 g/cm(2) (ultradistal site). A steady BMD decline followed reaching 0.492 +/- 0.064 g/cm(2) at the distal and 0.412 +/- 0.069 g/cm(2) at the ultradistal site in age group >70. Age had a rather weak negative impact on forearm BMD described by a linear model. In men aged over 50 years the prevalence of osteoporosis at the distal site was 21.19%, compared to 20.45% in women. Low bone mass was seen in 48.77% of men and 32.50% of women. Normal BMD was more frequent in women (47.05%) than in men (30.04%).

CONCLUSIONS

We found a high prevalence of forearm osteoporosis in Bulgarian men which is comparable to that already known in women.

Significance of primary hyperparathyroidism in the management of osteoporosis

Primary hyperparathyroidism (HPT) has catabolic effects on cortical bone and anabolic effects on cancellous bone with overall deleterious effects on skeleton. Primary HPT is associated with increased fracture risk both at the cancellous bone-enriched spine and the cortical bone-enriched distal one third of the radius. This risk is reversed by parathyroidectomy.

Complex segregation analyses of bone mineral density in Chinese

China has the largest population in the world; approximately 7% of the total population suffers from primary osteoporosis. Osteoporosis is mainly characterized by low bone mineral density (BMD). In the present study, familial correlation and segregation analyses for spine and hip BMDs have been undertaken for the first time in a Chinese sample composed of 401 nuclear families with a total of 1260 individuals. The results indicate a major gene of additive inheritance for hip BMD, whereas there is no evidence of a major gene influencing spine BMD. Significant familial residual effects are found for both traits, and heritability estimates (+/-SE) for spine and hip BMDs are 0.807(0.099) and 0.897(0.101), respectively. Sex and age differences in genotype-specific average BMD are also observed. This study provides the first evidence quantifying the high degree of genetic determination of BMD variation in the Chinese.

Impact of using the ultradistal radius region of interest on diagnostic classification

World Health Organization (WHO) criteria using T-scores for classifying patients as normal, osteopenic, or osteoporotic are based on bone mineral density (BMD, g/cm2) of the lumbar spine and hip and bone mineral content (BMC) (BMC, g) at the distal and midradius. There is no consensus on whether other forearm regions of interest (ROIs) can be used with the WHO criteria. Because the ultradistal radius region of interest (UDR) has a greater ratio of trabecular to cortical bone than midshaft portions of the radius, it is possible that more patients would be classified as osteoporotic if the UDR is measured. The objective of this study was to determine the prevalence of osteoporosis when using T-scores from the UDR in addition to PA lumbar spine, proximal femur (hip), and the radius 33% ROI. Retrospective data were obtained from three centers with differing patient demographics, thus reducing bias as a result of patient characteristics. Data were used only from patients who had a spine, hip, and forearm scan on the same day. Central dual-energy X-ray absorptiometry (DXA) systems included a GE Lunar DPX-L, DPX IQ, and Prodigy and a Hologic Delphi. Hologic data were for the ultradistal radius + ulna ROI (UDRU). Diagnostic classification (using the WHO T-score criteria) was made excluding and including the UDR and UDRU T-scores, in addition to lumbar spine (L2-L4 or L1-L4), hip (femoral neck, greater trochanter, or total), and the radius 33% ROI. The lowest T-score from any ROI determined the classification. For all GE Lunar patients (n = 409 women; age range: 20-96 yr), the distribution of normal, osteopenic, osteoporotic not using the UDR was 94 (23%), 170 (42%), and 145 (36%), respectively. The distribution when using the UDR was 67 (16%), 137 (33%), and 205 (50%), respectively. The difference in the ratio of normal + osteopenic versus osteoporotic when excluding and including the UDR T-scores was significant (p < 0.0001; two-tailed Fisher's exact test). For all Hologic patients (n = 153 women; age range: 44-93 yr), the distributions were 32 (21%), 66 (43%), and 55 (36%) not using and 31 (20%), 64 (42%), and 58 (38%), respectively, using the UDRU (not statistically significantly different). The group mean T-scores were lowest for the UDR compared to the spine and hip with GE Lunar but not Hologic patients.