Stones and bones: Evaluating the impact of metabolic stone disease on bone health
Jennifer Bjazevic1, Fernanda Gabrigna Berto1, William Luke1, Linda Nott1, Hassan Razvi1.
1Department of Surgery, Western University, London, ON, Canada
Introduction: Urolithiasis is associated with lower bone mineral density (BMD), the development of osteopenia and osteoporosis, and fragility fractures. Our study aimed to further delineate the prevalence of low BMD in a metabolic stone population and to characterize metabolic risk factors.
Methods: A retrospective analysis of a prospectively maintained metabolic stone clinic database from September 2001 to December 2019 was performed. Patients who underwent BMD testing with a dual-energy X-ray absorptiometry (DEXA) scan were reviewed and correlation between BMD and metabolic parameters were determined with multivariate regression analysis.
Results: A total of 898 patients had a mean age of 54±14 years, were 54% male, and had a mean body mass index of 29.8±7. Calcium oxalate was the predominate stone composition (60%), followed by uric acid (16%) and calcium phosphate (11%). Metabolic abnormalities included hypercalciuria (57%), hypocitraturia (38%), primary (2%) and secondary (9%) hyperparathyroidism, complete (2%) and incomplete (13%) distal RTA, and vitamin D deficiency (78%). In our cohort, 17.6% of patients underwent BMD testing and included only a minority of patients (3%) who were eligible for DEXA scans based on age criteria alone. The majority of patients with DEXA scans (64%) had evidence of decreased BMD, including 50% with osteopenia, 11% with osteoporosis, and 3% with severe osteoporosis. There was no female predominance of decreased BMD in our series. Multivariate regression analysis did not identify any correlation between specific metabolic parameters and BMD scan results.
Conclusions: Metabolic stone formers have a high prevalence of low BMD and are at a high risk of poor bone health outcomes. Our series demonstrated that the true prevalence of this condition is likely significantly under-recognized, given that only a minority of eligible patients underwent BMD testing. Further research is required to develop optimal treatment strategies to mitigate the risks of poor bone health and recurrent urolithiasis.
