Systemic and Local Factors Effecting on the Bone Mineral Density of Patients with Rheumatoid Arthritis

慢性関節リウマチ(RA)患者の骨密度に影響を及ぼす全身的および局所的因子を調べるために,40人のRA患者について,脊椎,橈骨,踵骨の骨密度を DXA法で測定し,また踵骨は超音波法でも測定した.これらの値から性,年齢で補正したZ値を求め,各部位の骨密度について比較した.次に血清中のインターロイキン6,TNF-α,インタクトオステオカルシン濃度,上肢,下肢機能障害の程度,およびステロイド剤と骨密度との関連を調べた.その結果,上下肢機能障害の程度がそれぞれの部位の骨密度と最も密接に関連しており,またステロイド服用者は超音波法で測定した踵骨のstiffness indexが有意に低下していた.以上の結果より,RA患者の骨密度の低下には局所の廃用性骨萎縮がもっとも関与し,またステロイド剤は骨の質に影響を及ぼしている可能性が示唆された.(リハ医学1999;36:537-543)To investigate the systemic and local factors effecting on the bone mineral density of patients with rheumatoid arthritis (RA), we measured the bone mineral density of forty patients with RA at spine, radius and calcaneus by the dual energy X-ray absorptiometry. Quantitative ultrasound was also performed to measure stiffness index of calcaneus. The Z-score of bone density was compared to the serum levels of interleukin6, TNF-α and intact osteocalcin, and to the activity of daily living which were separately assessed by upper or lower limb function. The effects of corticosteroid were also examined. The decrease in bone mineral density was the most prominentin calcaneus (Z score=-1.3), and was minimal in spine(Z score=-0.2). There was no relationships between the serum levels of cytokines or intact osteocalcin and bone mineral density except a third distal of the radius. The function of upper or lower limb correlated with the bone mineral density of respective limb. The influence of corticosteroid appeared to decrease the stiffness index of calcaneus. These results showed that disuse of the extremity was the most important factor for osteoporosis of patients with RA and that corticosteroid seemed to have relations with the quality of bone. (Jpn J Rehabil Med 1999;36:537-543