The Correlation between Lumbar Bone Density and Kidney Stone Size Based on CTScan; a Retrospective Stud - Abstract
Background: Previous studies have recognized the association between nephrolithiasis and several systemic conditions, such as low bone mineral density (BMD). With non-contrast CT scans routinely performed as a part of urinary stone evaluation, the aim of this study is to assess the relation between the noncontrast CT based BMD and the stone size of patients with urinary Stones. Methods: In this retrospective study, 391 urinary stone patients who had undergone stone removal surgery between the years of 2013-2018, had a major calcium stone component and CT-imaging were enrolled. Stone size was defined as the maximum collected stone diameter on CT. BMD for each subject was calculated at the L1 vertebral level, with the CT attenuation being measured in Hounsfield Units (HU). As instructed by prior literature, a cut-off of 160 HU was selected to distinguish the normal BMD from the low BMD. Results: Our analysis showed a significant statistical association between stone size and BMD (P < 0.005). Furthermore, when dividing subjects under 3 subgroups of stone size (smaller than 20 mm, between 20 and 30 mm, larger than 30 mm), lower BMD was more prevalent among those with lager stones. Additional analysis demonstrated no meaningful association between stone size and basic patient variables (Age, gender, BMI), thus proving the independence of the relation between stone size and BMD. Conclusion: Larger stones are associated with lower CT-based BMD in urinary stone patients. Therefore, patients with larger stones are at a higher risk for osteoporosis, and should be properly assessed.