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Kidney Week

Abstract: SA-PO1052

Diet Dependent Systemic Acid Load (AL) Impacts Decline in Kidney Function Through Serum Albumin (SA)

Session Information

Category: Health Maintenance, Nutrition, and Metabolism

  • 1302 Health Maintenance, Nutrition, and Metabolism: Clinical

Authors

  • Banerjee, Tanushree, San Francisco General Hospital , San Francisco, California, United States
  • Sebastian, Anthony, University of California San Francisco, San Francisco, California, United States
  • Powe, Neil R., Priscilla Chan and Mark Zuckerberg San Francisco Gen Hosp & UCSF, San Francisco, California, United States
  • Frassetto, Lynda A., University of California San Francisco, San Francisco, California, United States
Background

Inflammation may be present with CKD and diet composition may affect inflammation thereby impacting kidney health. Higher intakes of proteins and fats yielding a higher AL have been linked with worsening of kidney function and inflammation may play a role. We investigated whether AL estimated from urine measures is associated with kidney function decline and whether the effect of AL on an inflammatory marker, SA, is a pathway to this association.

Methods

We studied 188 post-menopausal women in a clinical trial of potassium bicarbonate treatment for up to 36 months. 24-hr urine and arterialized blood collections were done at baseline and at subsequent 3 month follow-up visits. AL was estimated from the urine potential renal acid load (UPRAL), calculated using measures of chloride, phosphate, sodium, potassium, calcium, and magnesium. Mixed effects (ME) model with random-intercept and slope was used to estimate subjects’ annual decline rate in creatinine clearance (CrCl) and eGFR. We used the ME model to estimate the association between (1) UPRAL and SA, and (2) SA and CrCl, adjusting for age, body mass index, systolic BP, and glucose. A Cox proportional regression model was used to study the relative hazard for decline in CrCl with UPRAL, adjusting for potential covariates and baseline CrCl. Our models were repeated with eGFR decline as the outcome.

Results

A 25 mEq/day increase in UPRAL was inversely associated with SA (95% CI:–0.01[–0.09;-0.0001; p=0.05]). SA was inversely associated with CrCl (p<0.05). During 28 months mean follow-up, 45 women (23.9%) had a rapid decline in kidney function (loss ≥5 ml CrCl/yr). For each 25 mEq/day increase in UPRAL, the risk of a rapid decline in CrCl increased by 17% (95% CI:1.06-1.28). Adjusting for potential confounders, the risk attenuated to 5% (1.02-1.14). Mediation analysis indicated that of the total effect of the association between UPRAL and CrCl, the proportion mediated by SA was 0.32 (i.e. 32%). Using eGFR, the proportion mediated by SA increased to 0.41.

Conclusion

Higher UPRAL was associated with lower SA as well as reduced kidney function in post-menopausal women. Our findings suggest inflammatory response may exert a modulatory effect on the association of UPRAL and kidney function and might be a potential pathway to explain the effects of systemic AL on kidney function decline.

Funding

  • Commercial Support