Login to Access Video or Poster Abstract: MP19-04
Sources of Funding: None

Introduction

Kidney stones are associated with systemic diseases, including cardiovascular disease and loss of bone mineral density (BMD). It has been suggested that vascular calcification (VC) may be part of this pathophysiology. Recent published data in a small, uniform cohort suggested that kidney stone formers (KSFs) had higher levels of VC then controls. We sought to clarify these findings in an ethnically diverse large case control study of KSFs and non-stone former controls.

Methods

Retrospective study of 672 KSFs and 253 non-stone former controls seen between 2004 and 2013 was conducted. Control patients were identified as patients without a history of kidney stones that had a non-contrast CT scan. VC was measured as Abdominal Aortic Calcification (AAC) between L1 and L4 vertebras on non-contrast CT images. Measurements were translated to a score via the use of a severity factor. BMD was measured at the L1 level. Osteoporosis was defined as ≤135 HU. Statistical analysis was performed using Student t-tests, Wilcoxon sign-rank test, Chi-square tests, and logistic regression models.

Results

AAC was present in 46% of KSFs and 54% of controls (p=0.02) with a lower median in KSFs compared to controls, 22.5 (5.64-129.20) vs. 105.3 (23.85-202.74), respectively (p<0.001). KSFs with AAC between 0 and 49.6 had 81% (p<0.001) increased risk of stones in a logistic regression model. Hispanic stone formers had lower AAC in comparison to non-Hispanics (15.3 vs. 25.6; p=0.04), and whites had a 2.32-fold increased risk of stones compared with others. AAC severity inversely correlated with BMD (r= -0.3; p<0.001), and KSFs had 50% increased risk of osteoporosis than controls (p=0.06). Interestingly, most KSFs (82%) and controls (93%) with osteoporosis had AAC present while 26% of those with normal BMD had AAC. Urinary calcium positively correlated with AAC (r= 0.14; p=0.014) and negatively with BMD (r= -0.16; p=0.008).

Conclusions

In contradistinction to previous reports, both AAC prevalence and AAC severity is greater in controls than KSFs. Interestingly, Hispanic stone formers had lower AAC severity, and whites had a higher risk of forming stones. Additionally, osteoporosis was highly prevalent alongside AAC. Though controls with osteoporosis had higher AAC severity, KSFs had increased risk of osteoporosis. Furthermore, the data regarding urinary calcium adds to the evidence that hypercalciuria is a predictive factor of BMD loss in KSFs. Our study of an ethnically diverse population strengthens the relationship between stones and AAC.

Funding

None