Longitudinal changes in bone mineral content and body composition in boys with Duchenne muscular dystrophy

ABSTRACTS / Bone 40 (2007) S22–S89

to the Metabolic Bone Clinic, Helsinki University Hospital. Data on clinical history were collected from hospital records. Patients were assessed for spinal compression fractures by standard spinal radiographs and by bone densitometry (Hologic Discovery A) derived Instant Vertebral Assessment (IVA) images. The visibility and morphology of each vertebra in IVA images was assessed by two readers and by a semi computerized software developed for the DXA scanner. The findings were compared with those in spinal radiographs and correlated with clinical parameters. Results: The visibility of vertebrae in IVA images was good in T8–L4 (over 96%) but compromised in the upper thoracic region (T4–T7, 87–92%) and was constantly inferior to that in standard radiographs (T4–L4, 97–100%). A total of 25 vertebral fractures were diagnosed by the readers in radiographs, but only 9 (36%) of these also in IVA images. The semi computerized software could not accurately detect vertebrae in most of the children; accuracy increased with increasing age, height and BMD but was not sufficient to detect vertebral fractures. Conclusions: The utility of DXA scanner derived images of the spine in vertebral fracture detection in children is limited by

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compromised visibility and poor diagnostic accuracy in the thoracic area. The semi computerized software is not suitable for pediatric use. These limitations should be kept in mind when assessing pediatric patients for osteoporosis. doi:10.1016/j.bone.2007.04.083

Longitudinal changes in bone mineral content and body composition in boys with Duchenne muscular dystrophy H. McDevitt 1, R. McWilliam 2, N. Quayum 2, S. Ahmed 1 1 Bone and Endocrine Research Group, Royal Hospital for Sick Children, Glasgow, United Kingdom 2 Neurology, Royal Hospital for Sick Children, Glasgow, United Kingdom Duchenne muscular dystrophy (DMD) is a genetic, degenerative disease primarily affecting voluntary muscles. The onset is in early childhood, with generalized weakness and muscle wasting of hips, pelvis, thighs and shoulders. Glucocorticoid

Figure. Lateral IVA-images of three children: (A) (7 years) good, (B) (11 years) poor, and (C) (14 years) excellent visibility. (A and C) with semi computerized software markings.

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ABSTRACTS / Bone 40 (2007) S22–S89

treatment is used to improve muscle strength and prolong ambulation. The aim of this study was to assess the longitudinal changes in bone area (BA), bone mineral content (BMC) and body composition measured by dual energy absorptiometry (DXA) in boys with DMD on glucocorticoid treatment. Total body (TB) and lumbar spine (LS) DXA were performed serially in 10 boys with DMD. Fat mass (FM) for height, lean mass (LM) for height, TB/LS BA for height, TB/LS BMC for height, bone area and lean mass were calculated using local reference data.

Z-score

Age Ht SDS BMI SDS LM for Ht FM for Ht TB BA for Ht TB BMC for BA TB BMC for Ht LS BMC for Ht LS BMC for BA LS BA for Ht

1st DXA n = 10

2nd DXA n = 10

3rd DXA n = 7

mean (SD)

mean (SD)

mean (SD)

8.4 (2.1) − 0.4 (1.2) 0.8 (1.5) 0.0 (1.5) 0.4 (0.9) − 0.7 (1.7) 0.0 (3.2) − 0.48 (1.5) − 0.2 (1.2) − 0.7 (1.8) 0.1 (1.2)

9.5 (2.1) − 0.4 (1.0) 1.1 (1.5)* − 0.5 (1.5)* 0.9 (1.2)* − 1.0 (1.7) − 1.4 (2.8)* − 0.9 (1.5)* − 0.7 (1.7)* − 0.8 (2.2) − 0.6 (1.0)*

11.5 (2.0) − 0.4 (1.3) 1.4 (0.4)** − 1.2 (1.0) 1.8 (1.0)** − 0.7 (1.2) − 4.5 (3.1)** − 1.4 (0.8) − 1.0 (0.6) 0.7 (3.4) − 1.8 (− 1.6)

*Significantly different from 1st measurement using paired t test (p b 0.05). **Significantly different from 2nd measurement using paired t test in the 7 patients who had both 2nd and 3rd DXAs (p b 0.05).

Boys with DMD and who receive glucocorticoid treatment show a rise in BMI and fat mass and a fall in lean mass. Although height was maintained in these children, BMC fell over the duration of the study. This was evident at both sites of measurement. The effect of DMD and glucocorticoids on growth and bone is discordant. doi:10.1016/j.bone.2007.04.084

Comparison of bone mineral density in children and adults with hypoparathyroidism J.E. Mckie 1, M.T. Collins 1, J.C. Reynolds 2, K.K. Winer 3 1 Craniofacial and Skeletal Diseases Branch, National Institutes of Health, Bethesda, MD 2 Nuclear Medicine, National Institutes of Health, Bethesda, MD 3 NICHD, National Institutes of Health, Bethesda, MD Hypoparathyroidism is associated with high bone mass in adults with this disorder. We studied the bone mass of children in comparison to adults with hypoparathyroidism. Bone mineral density (BMD) was studied in children at baseline and in response to 3 years of treatment with synthetic human parathyroid hormone 1–34 (PTH) vs. calcitriol + calcium in 14 children in a randomized parallel group design. These values were compared to the previously published data in 28 adults (Winer et al., 2003), who were treated in the same 3-year study.

The BMD of the anterior-posterior lumbar spine (APLS), femoral neck (FN), and total hip (TH) were measured by dual X-ray absorptiometry (DXA) and Z-scores between children and adults were compared, using the current Hologic pediatric database. All patients were on calcitriol + calcium therapy for at least a year before protocol entry. Our results showed that at baseline both children and adults had increased BMD. While the children’s baseline BMD Z-scores were consistently lower than the adults, this difference was not significant. The duration of hypoparathyroidism had a significant effect on APLS and TH BMD values in adults, but not in children. After 3 years of PTH therapy, children demonstrated a significant decrease in BMD at the APLS (p b 0.05), and a trend towards lower BMD in the FN and TH. In children treated with calcitriol + calcium, and in all adults (both PTH and calcitriol + calcium treated) BMD increased. The increase was significant only in adults treated with calcium + calcitriol in the FN and TH (p b 0.05). Interestingly, when the data were analyzed with the original Hologic pediatric database, all Z-scores were lower for the children and all comparisons were different. In conclusion, bone mass in children with hypoparathyroidism is elevated, and there appears to be a difference in the response to PTH of children compared to adults. doi:10.1016/j.bone.2007.04.085

Site-specific differences in bone mass between SA children of different ethnic groups L.K. Micklesfield 1, S.A. Norris 2, D.A. Nelson 3, E.V. Lambert 1, L. van der Merwe 4, J. Pettifor 5 1 Department of Human Biology, University of Cape Town, Cape Town, South Africa 2 Mineral Metabolism Research Unit, University of Witwaterstrand, Johannesburg, South Africa 3 Department of Internal Medicine, Wayne State University, Detroit, MI 4 Medical Research Council, Cape Town, South Africa 5 Mineral and Metabolic Research Unit, University of Witwaterstrand, Johannesburg, South Africa We have previously shown that although younger, shorter and lighter, whole body bone mineral content is greater in SA children of mixed ancestral origin compared to black and white US and SA children. To more closely investigate site-specific differences between ethnic groups within South Africa, we compared lumbar spine (LSBMC), proximal femur (PFBMC) and femoral neck (FNBMC) bone mineral content in black (SAB; n = 263) and white (SAW; n=73) children from Johannesburg, and in children of mixed ancestral origin (SAM; n = 64) from Cape Town, South Africa. SAW and SAB groups were slightly older (SAW: 9.5 ± 0.3; SAB: 9.6 ± 0.3; SAM: 9.3 ± 0.6 years) and heavier than the SAM group. There was no significant difference in mean body weight between the girls, however SAM boys were lighter than the other two groups. In what follows, “adjusted” indicates that