Objective: To investigate the mechanism underlying systemic lupus erythematosus (SLE)-related bone loss by evaluating the bone mineral density (BMD) and bone turnover markers (BTMs) in premenopausal patients with new-onset SLE without any treatment.
Methods: BMD and BTMs of 106 premenopausal patients with new-onset SLE and 64 gender-, age- and body mass index (BMI)-matched healthy controls were analyzed. BMD was determined using dual energy X-ray absorptiometry (DXA). Serum BTMs were measured.
Results: Hip and lumbar spine BMD in premenopausal patients with new-onset SLE was significantly decreased compared with healthy controls. Higher rate of osteoporosis was observed in new-onset SLE patients (25% vs. 1%). Moreover, uncoupled bone remodeling evidenced by an increase in bone resorption marker β-CTX (685.9 ± 709.6 pg/mL vs. 395.4 ± 326.0 pg/mL, P < 0.05) and decrease in bone formation markers PINP (37.4 ± 33.0 ng/mL vs. 46.1 ± 20.9 ng/mL, P < 0.05) and OC (11.4 ± 9.8 ng/mL vs. 18.2 ± 8.6 ng/mL, P < 0.05) was observed in premenopausal patients with new-onset SLE compared with healthy controls. Univariate correlation analyses showed negative correlations between OC and SLE Disease Activity Index (SLEDAI), and positive correlations between β-CTX and SLEDAI. SLE patients positive for dsDNA, nucleosome showed lower OC and higher β-CTX.
Conclusion: Premenopausal patients with new-onset SLE had decreased BMD and abnormal bone metabolism with increased β-CTX and decreased OC and P1NP levels, indicating uncoupled bone remodeling in new-onset SLE patients. Disease activity and abnormal immunity, especially the amount of antibodies in SLE patients, were strongly associated with abnormality of bone metabolism.
Keywords: Premenopausal systemic lupus erythematosus; bone formation; bone mineral density; bone resorption.