Bone mineral density in women with ankylosing spondylitis

OBJECTIVE: To determine bone mineral density (BMD) in premenopausal women with early ankylosing spondylitis (AS). METHODS: Eighteen premenopausal women with AS without syndesmophytes, interapophysiary arthritis, and/or coxofemoral joint destruction were studied. BMD was analyzed at lumbar spine and femoral neck by dual energy x-ray absorptiometry (Hologic QDR 1000). Z scores and T scores related to the general Spanish population were recorded. Comparisons were performed using the Student t test. Pearson's correlation coefficients were used to study the correlation between BMD and the variables. Following the WHO classification, osteopenia was diagnosed in patients with T score between -1 and -2.5 and osteoporosis in those with T score < -2.5 at lumbar spine or femoral neck. RESULTS: The mean Z score for spine BMD was -0.19+/-0.7, and -0.03+/-0.85 for femoral neck BMD. There were no significant differences of Z score values compared to the general population. No significant correlation was found between BMD and disease duration, radiology sacroiliac score, and spine mobility. Densitometry showed osteopenia in 2 patients and osteoporosis in none. CONCLUSION: We found a slight reduction in BMD in premenopausal women with early AS, but the difference was not statistically significant. We discuss the factors related to its pathogenesis.