Rheumatology and Clinical Immunology, University Medical Center Groningen, University of Groningen, P.O. Box 30001, 9700 RB Groningen, The Netherlands.
Osteoporos Int. 2011 May;22(5):1431-9. doi: 10.1007/s00198-010-1338-7. Epub 2010 Jul 6.
Osteoporosis is a well recognized complication of ankylosing spondylitis (AS). This study indicates that increased bone turnover, inflammation, and low vitamin D levels are important in the pathophysiology of AS-related osteoporosis, and that bone turnover markers (BTM) are valuable markers to detect bone loss in AS.
The aim of this study was to elucidate the pathophysiology of AS-related osteoporosis by investigating the relation between bone mineral density (BMD), BTM, vitamin D, and clinical assessments of disease activity and physical function, as well as to identify parameters that are related to low BMD (osteopenia or osteoporosis) in AS patients with active disease.
One hundred twenty-eight consecutive Dutch AS outpatients were included in this cross-sectional study. Bath AS Disease Activity Index (BASDAI), erythrocyte sedimentation rate (ESR), C-reactive protein, ASAS-endorsed disease activity score (ASDAS), Bath AS Functional Index (BASFI), bone formation markers procollagen type 1 N-terminal peptide (PINP) and osteocalcin (OC), bone resorption marker serum C-telopeptides of type I collagen (sCTX), 25-hydroxyvitamin D (25OHvitD), lumbar spine and hip BMD, and vertebral fractures were assessed. Z-scores of BTM were calculated using matched 10-year cohorts of a Dutch reference group to correct for the normal influence that age and gender have on bone turnover.
sCTX Z-score, OC Z-score, BASDAI, age, and gender were independently related to low BMD. In addition, PINP Z-score, ESR, 25OHvitD, age, and gender were independently related to sCTX and/or OC Z-score.
This study indicates that increased bone turnover, inflammation, and low vitamin D levels are important in the pathophysiology of AS-related osteoporosis. Furthermore, sCTX and OC Z-scores seem to be valuable markers to detect bone loss in AS patients in daily clinical practice where BMD of the lumbar spine, measured by DXA, may be overestimated due to osteoproliferation in patients with advanced AS.
骨质疏松症是强直性脊柱炎（AS）的一种公认并发症。本研究表明，骨转换增加、炎症和低维生素 D 水平在 AS 相关骨质疏松症的病理生理学中很重要，骨转换标志物（BTM）是检测 AS 患者骨丢失的有价值的标志物。
本研究旨在通过研究骨密度（BMD）、BTM、维生素 D 与疾病活动和身体功能的临床评估之间的关系，阐明 AS 相关骨质疏松症的病理生理学，并确定与活动期 AS 患者低 BMD（骨质疏松或骨量减少）相关的参数。
本横断面研究纳入了 128 例连续的荷兰 AS 门诊患者。评估了 Bath AS 疾病活动指数（BASDAI）、红细胞沉降率（ESR）、C 反应蛋白、ASAS 认可的疾病活动评分（ASDAS）、Bath AS 功能指数（BASFI）、骨形成标志物 1 型前胶原 N 端肽（PINP）和骨钙素（OC）、骨吸收标志物血清 I 型胶原 C 端肽（sCTX）、25-羟维生素 D（25OHvitD）、腰椎和髋部 BMD 以及椎体骨折。使用荷兰参考队列的 10 年匹配队列计算 BTM 的 Z 分数，以校正年龄和性别对骨转换的正常影响。
sCTX Z 分数、OC Z 分数、BASDAI、年龄和性别与低 BMD 独立相关。此外，PINP Z 分数、ESR、25OHvitD、年龄和性别与 sCTX 和/或 OC Z 分数独立相关。
本研究表明，骨转换增加、炎症和低维生素 D 水平在 AS 相关骨质疏松症的病理生理学中很重要。此外，sCTX 和 OC Z 分数似乎是检测 AS 患者骨丢失的有价值的标志物，在日常临床实践中，由于 AS 晚期患者的骨增生，DXA 测量的腰椎 BMD 可能会被高估。
