Relationship between renal stone formation, mitral annular calcification and bone resorption markers

BACKGROUND AND OBJECTIVES: Mitral annular calcification (MAC) is associated with osteoporosis and there is evidence of reduced bone mineral density (BMD) in patients with renal stone formation (RSF). Therefore, we designed this study to test if RSF was associated with MAC and if this association could be linked to bone resorption. METHODS: Fifty-nine patients (mean age, 41.5 years) with RSF and 40 healthy subjects (mean age, 44.2 years) underwent screening for MAC and BMD, and measuurements were taken of serum and urine electrolytes, parathyroid hormone, alkaline phosphatase and urine dypyridoline. RESULTS: MAC was diagnosed in 11 (18%) patients with RSF compared with 1 (2.5%) control (P=.01). Urine phosphorus, magnesium, sodium, potassium and chloride levels were lower (P<.001, P=.02, P<.001, P<.001 and P<.001, respectively), but serum alkaline phosphatase, calcium and potassium levels were higher (P=.008, P=.007 and P=.001, respectively) in patients with RSF versus those without RSF. None of these abnormalities were found in patients or subjects with MAC. Urine pyridoline levels were higher and T-scores were more negative (more osteopenic) in patients and subjects with MAC than in those without MAC (P=.01 and P=.004, respectively). In a multivariate analysis, only T-scores and urine dipyridoline level were predictive of MAC (P=.03 and P=.04, respectively). CONCLUSIONS: Screening for MAC and bone resorption markers in patients with RSF demonstrated a high incidence of MAC in these patients. The presence of MAC in patients with RSF was associated with bone resorption markers. This seemingly complex interrelationship between RSF, MAC and bone loss needs to be clarified in further studies.