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Abstract: PO0580

Impact of Urinary Calcium Excretion on Bone, Cardiovascular System, and Kidney Function in Caucasian Osteoporotic Patients: A Longitudinal Long-Term Follow-Up Study

Session Information

Category: Bone and Mineral Metabolism

  • 402 Bone and Mineral Metabolism: Clinical

Authors

  • Parikh, Tapas, University of Kentucky Medical Center, Lexington, Kentucky, United States
  • Abdalbary, Mohamed Mamdouh, Mansoura University Faculty of Medicine, Mansoura, Egypt
  • Chishti, Emad A., University of Kentucky Medical Center, Lexington, Kentucky, United States
  • Shakhashiro, Muna, University of Kentucky Medical Center, Lexington, Kentucky, United States
  • Faugere, Marie-Claude M., University of Kentucky Medical Center, Lexington, Kentucky, United States
  • Sawaya, B. Peter Emile, University of Kentucky Medical Center, Lexington, Kentucky, United States
  • Mohamed, Amr El-Husseini, University of Kentucky Medical Center, Lexington, Kentucky, United States
Background

Urinary Calcium excretion (UCaE) is expected to reflect the bone activities, however this relationship in osteoporotic (OP) patients (pts) is not well understood. Moreover, the influence of UCaE on kidney function and cardiovascular (CV) system is controversial.

Methods

Longitudinal study for OP pts who had bone biopsies between January 2008 and December 2013. All pts were white, had 24 urine collection for UCaE, DEXA scan for BMD, bone histology, and at least two follow ups with a minimum of 1-y. Exclusion criteria included active malignancies and infections, liver failure, ESKD, organ transplant, or secondary OP.

Results

Study included 118 OP pts with median follow up of 5.3 (1-11) y. The mean age was 61 ± 12 y and 89% of pts were women. The mean eGFR at baseline was 83 ± 19 ml/min. Trabecular bone volume was low in 95% of pts, 39% had high turnover bone turnover disease (HTBD) and 61% had low turnover bone disease (LTBD), while mineralization was defective in 9%. Serum calcium and 25 vitamin D were within normal range in vast majority of pts. At baseline, lumbar spine (LS) T-score was -1.9 (-5.5 to 3.9), and total hip (TH) T-score was -1.6 (-4 to 2). Pts with HTBD had lower LS T-scores (p=0.02). Hypercalciuria found in 23%. Mean UCaE was 195 ± 116 mg/d with no difference between LTBD and HTBD pts. CKD pts were older (p<0.001), had higher PTH (p<0.001), and lower UCaE (p=0.04).
BMD significantly declined (>2%) in 46% of pts at TH, and 42% at LS. BMD losers at TH were older, had lower UCaE, and lower serum albumin. Lower UCaE was significant predictor of BMD loss after adjustment of age, eGFR, and serum albumin (p=0.039, β=1.01, 95% CI (1-1.01)). Fractures occurred in 18% of pts during follow up. Fractures were higher in pts with UCaE<100. GFR declined (>3.3%/y) in 19% pts with no difference in UCaE in pts with declined vs stable GFR. Pts with kidney stones (13%) tended to have higher UCaE. New CV events occurred in 14% of pts. Pts with CV events tended to be older (64 vs 61 y) and had lower UCaE (169 vs 199 mg/d).

Conclusion

LTBD is common in OP pts. UCaE is not different between LTBD, and HTBD pts. CKD pts had less UCaE. Lower UCaE predicted bone loss and fracture risk in white OP pts.