The Citrate and Oxalate Association Is Likely Driven by Diet

Background: Higher urine oxalate excretion has been associated with higher urine citrate excretion. The mechanism for this association may be due to simultaneous dietary intake oxalate and citrate in food or transporter linkage of SLC26A6 and NaDC1 in the kidney. Methods: Nineteen participants were admitted to the clinical research center and given sodium oxalate. Timed pre-sodium oxalate (3) and post-sodium oxalate (6) urine samples were collected every hour. Fourteen participants also consumed a low oxalate, low citrate breakfast at the time of the sodium oxalate and 5 participants remained fasting for the duration of the protocol. Means of baseline values and ratios of oxalate (mmol)/creatinine (mg) and citrate (mmol)/creatinine (mg) were calculated. Mean and standard error were graphed per period and mixed methods longitudinal models were generated to compare change over time versus pre-oxalate value (mean 3 values, Period 1). Results: Ten of the 19 participants were female with mean age 54 years. For the 14 who had breakfast, urine oxalate/creatinine was higher than baseline in periods 3, 5, and 6 and urine citrate/creatinine was higher than baseline in periods 4 and 5 (Figure 1A and 1B). For the 5 who had no breakfast, urine oxalate was higher than baseline in periods 3, 5, 6, and 7 and urine citrate did not increase above baseline in any period (Figure 2A and 2B). Conclusion: After consumption of sodium oxalate participants had a rise in urine oxalate excretion, as expected. However, only participants who had food at the time of sodium oxalate administration also had a rise in urine citrate. The association between oxalate and citrate excretion is likely driven by dietary intake though additional participants need to complete the protocol. Funding: NIDDK Support