X-ray absorptiometry of bone in obese and eutrophic children from Valparaiso, Chile.

Objective: To assess and compare bone mineral content (BMC) and bone mineral density (BMD) by dual X-ray absorptiometry (DEXA) measurement in obese and eutrophic children.

Methods: In a cross sectional, case control study 16 obese children (8 male, 8 female) aged 5 to 13 years were recruited from the outpatient nutrition clinic of Carlos van Buren Hospital, Valparaiso, Chile, during 1997. Sixteen healthy eutrophic children matched for sex, chronological age, height, and pubertal stage were enrolled as controls. The mean dietary calcium intake was 580 +/- 100 mg/day. All obese patients had more than 2 standard deviation (SD) of height/weight ratio. Lumbar spine (L2-L4) BMD, femoral neck BMD, total body BMD, and total body BMC were measured by posteroanterior dual photon DEXA. The results were expressed as mean +/- SD. Comparison of the data was determined by Wilcoxon and Student t test.

Results: Mean BMC was 1684.1 +/- 492.38 g in obese children and 1418.2 +/- 483.48 g in controls (p < 0.001, Student t test; p = 0.001, Wilcoxon test). Mean total BMD was 817.5 +/- 99.37 g/cm2 in obese children and 771.62 +/- 105.62 g/cm2 in controls. (p = 0.041 by Wilcoxon). Mean hip BMD was 784.4 +/- 117.05 g/cm2 in obese children and 801.67 +/- 150.34 g/cm2 in controls. Mean spine BMD was 724.87 +/- 171.75 g/cm2 in obese children and 686 +/- 137.08 g/cm2 in controls (not significant).

Conclusion: Obese children have more total body BMC than eutrophic children. There was no significant difference in regional hip BMD and lumbar spine BMD among obese and normal children. Obese children may have larger bones.