Abstract: TH-PO1064

Determinants of Reduced Urinary Calcium Excretion in Patients with CKD: The Role for 1.25-VitD

Session Information

Category: Mineral Disease

  • 1201 Mineral Disease: Ca/Mg/PO4

Authors

  • Ramalho, Janaina de Almeida Mota, Nephrology Division, Faculty of Medicine, University of São Paulo, São Paulo, Brazil
  • Duarte, Estela Mion petrillo, Nephrology Division, Faculty of Medicine, University of São Paulo, São Paulo, Brazil
  • Takeichi, Ana Paula menossi, Nephrology Division, Faculty of Medicine, University of São Paulo, São Paulo, Brazil
  • Machado, Alisson Diego, Nephrology Division, Faculty of Medicine, University of São Paulo, São Paulo, Brazil
  • Lotufo, Paulo, Clinical Research Center, Universitary Hospital, University of São Paulo, São Paulo, Brazil
  • Bensenor, Isabela M., Clinical Research Center, Universitary Hospital, University of São Paulo, São Paulo, Brazil
  • Moyses, Rosa M.A., Nephrology Division, Faculty of Medicine, University of São Paulo, São Paulo, Brazil
  • Titan, Silvia M., Nephrology Division, Faculty of Medicine, University of São Paulo, São Paulo, Brazil
Background

A positive calcium balance may contribute to the pathogenesis of vascular calcification, which is highly prevalent in CKD. Recent studies have shown that CKD is associated with a reduction in urinary calcium excretion (UCE), but determinants are not fully known. Our aim was to evaluate mineral metabolism biomarkers associated with UCE in a CKD population.

Methods

Clinical data, CKD-MBD biomarkers and 24h urinary calcium excretion from 412 participants in the Progredir Study were evaluated. Univariable and multivariable linear regression models were used to explore determinants of UCE expressed in mg/kg – log transformed.

Results

Median UCE was 0.48 mg/kg (IQR 0.28 – 0.82 mg/kg). In the descriptive analysis, calciuria was negatively related to age, serum phosphorus, serum potassium, PTH, FGF23, and acidosis, whereas positively associated to eGFR, serum calcium, and 1,25-vit D. In linear regression models, even after adjustment for age, sex and eGFR, only 1,25-vit D, serum calcium, serum potassium and acidosis remained significantly related to UCE. However, in the multivariable model (Table1), only age, eGFR, 1.25-VitD and serum calcium were independently related to UCE.

Conclusion

Our results show that eGFR decline is associated with a dramatic decrease in UCE. Age, 1.25-VitD and serum calcium are independently associated to this effect in this CKD population. Therapeutic measures on 1.25-VitD reduced levels could have an impact on UCE.

Table 1. Multivariable linear regression model on UCE(log)
 B95% CI Bp value
Age -0.003-0.0060.05
eGFR-CKDEPI0.0060.003<0.0001
Bicarbonate0.008-0.0040.20
K-0.05-0.120.11
Total Calcium0.130.07<0.0001
1.25-VitD0.0040.0010.009

Funding

  • Government Support - Non-U.S.