Increased bone resorption and failure to respond to antiresorptive therapy in progressive dystrophic calcification.

The aim of this study was to evaluate strategies to halt the progression of severe dystrophic calcification in a patient with progressive systemic sclerosis (PSS) and to monitor serial changes in biochemical markers of bone resorption and indices of calcium (Ca) metabolism in response to therapy. The relationship of bone turnover to the extent of dystrophic calcification was also investigated in a number of additional patients with varying degrees of calcinosis. Serial markers of bone turnover and indices of Ca metabolism were measured over a 3-year period in one patient with PSS and severe dystrophic calcification. Bone mineral density (BMD) was assessed by dual-energy x-ray absorptiometry (DXA). Bone turnover in this patient and two additional patients with PSS or dermatomyositis (DM) and severe dystrophic calcification (Group A, n = 3) was compared with that in patients with connective tissue disease with little or no evidence of dystrophic calcification (Group B, n = 13). Serial data on one patient with severe progressive calcinosis showed increased bone resorption markers, which remained high over a 3-year period despite antiresorptive therapy. BMD was low. Patients with PSS/DM with severe dystrophic calcification had higher bone resorption than those with minimal or no evidence of calcification. Mean serum ionized Ca and urinary Ca excretion were both lower in those with severe calcinosis. Bone resorption was increased in patients with connective tissue disease and severe dystrophic calcification. Several antiresorptive agents were shown to be ineffective in limiting either bone turnover or clinical progression in one patient.