Bone mineral density and biochemical markers of bone metabolism in ankylosing spondylitis

Objective. To determine (1) bone mineral density (BMD) of the axial and appendicular skeleton in men with moderate and severe ankylosing spondylitis (AS), and (2) associations between BMD and bone metabolism variables. Methods. Nineteen men with AS and 19 healthy male controls were evaluated for osteoporosis by dual energy x-ray absorptiometry in both the hip and the lateral and posterior-anterior (PA) projections of the lumbar spine. Calcium homeostasis was evaluated by measuring minerals, calcitropic hormones, and markers of remodeling. Total testosterone levels were also measured. Results. Osteopenia was noted in both the hip and spine of the subjects with AS. The lateral projection of L3 was a more sensitive indicator of the vertebral BMD compared to the PA projection. Calcium homeostasis and testosterone levels were normal in subjects with AS. In most subjects, markers of bone formation and resorption were normal. Conclusion. BMD of subjects with AS is decreased, in spite of normal calcium homeostasis and bone remodeling indices.