Abstract: TH-PO1140

Dietary Acid Load Is Associated with Greater Urinary Nitrogen and Muscle Mass Loss in CKD Patients

Session Information

Category: Fluid, Electrolytes, and Acid-Base

  • 704 Fluid, Electrolyte, Acid-Base Disorders

Authors

  • Angeloco, Larissa Rodrigues Neto, University Of São Paulo, Ribeirao Preto, Brazil
  • Banerjee, Tanushree, University of California, San Francisco, San Francisco, California, United States
  • Frassetto, Lynda A., University of California San Francisco, San Francisco, California, United States
Background

In chronic kidney disease (CKD), high dietary acid loads may promote metabolic acidosis, which in turn may contribute to adverse clinical health outcomes. We hypothesize that high diet acid load plus higher acid body content in CKD leads to greater muscle breakdown and greater urine nitrogen loss. We examined associations between dietary acid load, serum bicarbonate, 24- hour urine urea nitrogen (UUN), arm muscle area (AMA), and diet protein/potassium (K) ratio in pre-dialysis CKD subjects.

Methods

100 subjects with CKD stage 3 and 4 and 29 healthy control subjects were enrolled in this cross-sectional study. Potential renal acid load (PRAL) and net acid excretion (NAE) were determined by the average of 3-day food records using the equations by Remer, Frassetto, and Lemann. PRAL and NAE were divided into quintiles. Pearson correlation and multivariable regression analysis were used to evaluate the associations of dietary acid measurements (PRAL and NAE) with serum bicarbonate, UUN, AMA, and diet protein/K ratio. The regression models were adjusted for demographics, body mass index, diabetes, systolic and diastolic blood pressure, urine pH, and creatinine clearance.

Results

Mean age of the population was 57 yrs (range 28-69) with 53% females. Median eGFR was 30 ml/min for the CKD subjects, and 100 ml/min for the controls. The correlation coefficients (p value) in CKD subjects in the highest quintile of diet acid load are presented (see table).

PRAL correlated significantly with UUN in the control subjects (r=0.9). In adjusted analysis, compared to the lowest quintile, no significant association was observed between the higher quintiles of PRAL with serum bicarbonate in CKD patients (β[95% CI]: -0.4[-2.5-1.7] in quintile 5, -0.4[-2.4-1.6] in quintile 4, -0.05[-1.9-1.8] in quintile 3, 1.3[-0.5-3.2] in quintile 2).

Conclusion

We found a significant association of higher body acid balance with urinary nitrogen loss, but not with serum bicarbonate. In patients with CKD, limiting diet acid load may improve metabolic acidosis and its long-term adverse health effects.

 24 hr UUNdiet protein/K ratioAMA
NAE (Frassetto)0.5 (0.04)0.5 (0.02)0.5 (0.03)
NAE (Remer)0.5 (0.01)0.6 (0.005)0.02 (0.3)
NAE (Lemann)0.5 (0.02)0.05 (0.8)0.1 (0.6)

correlation coeffient (p value)

Funding

  • Private Foundation Support