A Comparison of Treating Metabolic Acidosis in CKD Stage 4 Hypertensive Kidney Disease with Fruits and Vegetables or Sodium Bicarbonate

Background and objectives Current guidelines recommend Na+-based alkali for CKD with metabolic acidosis and plasma total CO2 (PTCO2) < 22 mM. Because diets in industrialized societies are typically acid-producing, we compared base-producing fruits and vegetables with oral NaHCO3 (HCO3) regarding the primary outcome of follow-up estimated GFR (eGFR) and secondary outcomes of improved metabolic acidosis and reduced urine indices of kidney injury. Design, setting, participants, & measurements Individuals with stage 4 (eGFR, 15-29 ml/min per 1.73 m(2)) CKD due to hypertensive nephropathy, had a PTCO2 level < 22 mM, and were receiving angiotensin-converting enzyme inhibition were randomly assigned to 1 year of daily oral NaHCO3 at 1.0 mEq/kg per day (n=35) or fruits and vegetables dosed to reduce dietary acid by half (n=36). Results Plasma cystatin C calculated eGFR did not differ at baseline and 1 year between groups. One-year PTCO2 was higher than baseline in the HCO3 group (21.2 +/- 1.3 versus 19.5 +/- 1.5 mM; P<0.01) and the fruits and vegetables group (19.9 +/- 1.7 versus 19.3 +/- 1.9 m.M; P<0.01), consistent with improved metabolic acidosis, and was higher in the HCO3 than the fruits and vegetable group (P<0.001). One-year urine indices of kidney injury were lower than baseline in both groups. Plasma [K+] did not increase in either group. Conclusions One year of fruits and vegetables or NaHCO3 in individuals with stage 4 CKD yielded eGFR that was not different, was associated with higher-than-baseline PTCO2, and was associated with lower-than-baseline urine indices of kidney injury. The data indicate that fruits and vegetables improve metabolic acidosis and reduce kidney injury in stage 4 CKD without producing hyperkalemia. din J Am Soc Nephrol 8: 371-381, 2013. doi: 10.2215/CJN.02430312