Kidney Week

Abstract: FR-PO431

Urinary Citrate Concentrations in a Multi-Ethnic Asian Population of Healthy Participants and CKD Patients

Session Information

• CKD: Risk Factors for Incidence and Progression - II
  November 03, 2017 | Location: Hall H, Morial Convention Center
  Abstract Time: 10:00 AM - 10:00 AM

Category: Chronic Kidney Disease (Non-Dialysis)

• 301 CKD: Risk Factors for Incidence and Progression

Authors

• Ngoh, Clara Lee Ying, University Medicine Cluster, National University Health System, Singapore , Singapore

Clara Lee Ying Ngoh,

• Teo, Boon Wee, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore

Boon Wee Teo,

Background

Hypocitraturia is a risk factor for nephrolithiasis. Urinary metabolomics from non-Asian centres have suggested that urinary citrate is important for chronic kidney disease (CKD) progression. We studied clinical associations between urinary citrate concentrations and CKD in a multi-ethnic Asian population.

Methods

Data of 187 CKD patients and 87 healthy participants from the Asian Kidney Disease Study and the Singapore Kidney Function Study were used. Four ethnic groups (Chinese, Malay, Indian and Others) were included. Glomerular filtration rate (eGFR) was estimated using the CKD Epidemiology Collaboration (CKD-EPI) equation. Urine citrate concentration was assayed using fluorescence mass-spectrometry. Hypocitraturia was defined as 24-hour urinary citrate excretion (UCE) <320 mmol.

Results

The mean 24-hour UCE in healthy controls and patients were 336 (209 - 443) mmol and 143 (63 - 208) mmol (CKD 1 and 2); 63 (17 - 93) mmol (CKD 3) and 21 (4 - 39) mmol (CKD 4 and 5) respectively (P <0.001). Hypocitraturia was first observed when eGFR <89 ± 12 ml/min/1.73 m². Hypocitraturia was also significantly associated with dietary protein intake (P =0.045), eGFR (P <0.001), metabolic acidosis (P <0.001) and 24-hour proteinuria (P <0.001).
In each CKD strata, Malay patients had the lowest 24-hour UCE (difference of 17 ± 24 mmol, P =0.025), after adjusting for age, eGFR, dietary protein intake and chronic medications. In the Malay population, 24-hour UCE was also associated with a history of coronary artery disease (P <0.001), but was not a risk factor for urolithiasis (P =0.590). In healthy controls, there were no ethnic disparities.

Conclusion

Hypocitraturia is observed in early CKD, with Asian ethnic disparities in terms of degree of UCE reduction. This has prognostic implications for renal and cardiac function. Further urinary metabolomics studies should focus on UCE to identify key signature differences between different Asian ethnic groups.