Rouster-Stevens Kelly A, Langman Craig B, Price Heather E, Seshadri Roopa, Shore Richard M, Abbott Kathy, Pachman Lauren M
Children's Memorial Hospital, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60614, USA.
Arthritis Rheum. 2007 Mar;56(3):977-83. doi: 10.1002/art.22433.
To determine bone mineral density (BMD) in patients at the time of diagnosis of juvenile dermatomyositis (DM), to compare the RANKL:osteoprotegerin (OPG) ratio in patients with juvenile DM with that in healthy control subjects, and to evaluate whether BMD is associated with the RANKL:OPG ratio and the duration of untreated disease.
Thirty-seven children with juvenile DM were enrolled. Dual x-ray absorptiometry (DXA) was performed before treatment, and Z scores for the lumbar spine (L1-L4) were determined. The duration of untreated disease was defined as the period of time from the onset of rash or weakness to the time at which DXA was performed. Serum specimens obtained at the time of DXA were analyzed for concentrations of RANKL and OPG, using enzyme-linked immunosorbent assay. The RANKL:OPG ratio was also determined in 44 age-matched healthy control subjects.
At the time of diagnosis of juvenile DM, patients had a significantly increased RANKL:OPG ratio compared with that in healthy children (mean +/- SD 2.19 +/- 3.03 and 0.13 +/- 0.17, respectively; P < 0.0001). In patients with a lumbar spine BMD Z score of -1.5 or lower, the RANKL:OPG ratio was significantly higher than that in patients with a lumbar spine BMD Z score higher than -1.5 (P = 0.038). Lumbar spine BMD Z scores (mean +/- SD -0.13 +/- 1.19 [range -2.10 to 2.85]) were inversely associated with the duration of untreated disease (R = -0.50, P = 0.003).
Children with juvenile DM have an elevated RANKL:OPG ratio at the time of diagnosis, resulting in expansion of the number of osteoclasts and activation of the bone resorptive function. This may lead to a lack of normal bone mineral accretion and a subsequent reduction in the lumbar spine BMD Z score. Patients with a longer duration of untreated juvenile DM have reduced lumbar spine BMD Z scores. These data suggest that early diagnosis could reduce the likelihood of reduced lumbar spine BMD in these patients by prompting intervention strategies at an early stage.
测定青少年皮肌炎（DM）患者诊断时的骨密度（BMD），比较青少年DM患者与健康对照者的核因子κB受体活化因子配体（RANKL）：骨保护素（OPG）比值，并评估BMD是否与RANKL：OPG比值及未治疗疾病的持续时间相关。
纳入37例青少年DM患儿。治疗前进行双能X线吸收测定（DXA），并确定腰椎（L1-L4）的Z值。未治疗疾病的持续时间定义为从皮疹或肌无力发作至进行DXA的时间段。使用酶联免疫吸附测定法分析DXA时采集的血清标本中RANKL和OPG的浓度。还测定了44例年龄匹配的健康对照者的RANKL：OPG比值。
青少年DM诊断时，患者的RANKL：OPG比值显著高于健康儿童（分别为均值±标准差2.19±3.03和0.13±0.17；P<0.0001）。腰椎BMD Z值为-1.5或更低的患者，其RANKL：OPG比值显著高于腰椎BMD Z值高于-1.5的患者（P=0.038）。腰椎BMD Z值（均值±标准差-0.13±1.19[范围-2.10至2.85]）与未治疗疾病的持续时间呈负相关（R=-0.50，P=0.003）。
青少年DM患儿诊断时RANKL：OPG比值升高，导致破骨细胞数量增加和骨吸收功能激活。这可能导致正常骨矿物质积累不足，随后腰椎BMD Z值降低。未治疗的青少年DM持续时间较长的患者腰椎BMD Z值降低。这些数据表明，早期诊断通过促使早期干预策略，可降低这些患者腰椎BMD降低的可能性。
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