Objective ① To investigate the level of the vitamin D endocrine system in peripheral relationships with bone mineral density (BMD) and the disease activity respectively. Methods The level of the 25-hydroxylate vitamin D3 (25OHD3) and 1,25-dihydroxyvitamin D3 [1,25(OH)D3] in plasma from 43 SLE patients and 44 normal controls were detected by enzyme linked immunosorbent assay. Vitamin D receptor (VDR) gene expression was determinied by real-time PCR in peripheral blood. BMD measurements in the lumbar spine (L1-4) and left proximal femur (femoral neck) were performed using dual X-ray absorptiometry before treatment. The relationship between the vitamin D endocrine system and the bone mass were studied. We also discussed the relationship between the vitamin D endocrine system and the disease activity. Results The levels of 25OHD3 and 1,25 (OH)2D3 were lower in the initial SLE patients than normal controls (P<0.01, P<0.01). The expressions of VDR gene were significantly increased in initial SLE compared with normal controls (P<0.01). The initial SLE patients had significantly lower BMD values, and higher frequency of osteopenia (35%) at both sites of measurement compared with matched healthy controls (P<0.01). The initial SLE patients were divided into two groups by BMD, abnormal group and normal group. There were no differences in 25OHD3, 1,25 (OH)D3 and VDR gene expression (P0.05). There was no correlation between the vitamin D endocrine system and BMD in initial SLE patients. There was no correlation between the vitamin D endocrine system and the disease activity either. Conclusion Vitamin D endocrine system may play an important role in SLE, but the level of VDR gene is not correlated with BMD and disease activity.

Department of Orthopedics, Yang Pu Hospital Affiliated to Tongji University,