Background: A relationship between osteoporosis and Down syndrome (DS) has been suggested. The causal mechanisms are unclear, but they could involve differences in the skeletal size.
Methods: Seventy-six patients with DS and 77 controls were included in the study. Spine and hip BMD values were assessed by dual-energy X-ray absorptiometry. Volumetric BMD was estimated by previously published formulas1 Serum 25OHD and iPTH levels were measured.
Results: The average age was 33 (18-64); 53% were men. Weight and height were lower in DS group (weight: 60 vs. 69 Kg; p<0.001 and height: 151 vs. 169 cm; p< 0.001), but BMI was higher in DS (26.5 vs. 24.1 kg/m2; p<0.001). Baseline 25OHD and iPTH levels were similar in both groups (22.7 [7.9] vs. 24.4 [9.6) ng/ml, p=0.25; and 24  vs. 26 (14) pg/ml, p=0.32, respectively). Similarly, the prevalence of hypovitaminosis D (25OHD<20 ng/ml) was similar in both groups (39% vs. 35%). Areal hip and spine BMD values were lower in people with DS. However, the estimated volumetric BMD was similar in both groups.
|Lumbar spine||DMO (g/cm2)||0.903 (0.117)||0.997 (0.121)||<0.05|
|DMOv (g/cm3)||0.244 (0.030)||0.255 (0.037)||0.061|
|Femoral neck||DMO (g/cm2)||0.761 (0.099)||0.838 (0.091)||<0.05|
|DMOv (g/cm3)||0.325 (0.068)||0.309 (0.043)||0.104|
Conclusion: Areal BMD is reduced in Down syndrome, but it seems to be related to the smaller body and skeletal size. In fact, the estimated volumetric BMD is similar in patients with Down syndrome and in control individuals.
Disclosure: The authors declared no competing interests.
1. Guijarro et al. (2008) J Intellect Disab Res.