Bicarbonate supplementation slows progression of CKD and improves nutritional status

Abstract

Bicarbonate supplementation preserves renal function in experimental chronic kidney disease (CKD), but whether the same benefit occurs in humans is unknown. Here, we randomly assigned 134 adult patients with CKD (creatinine clearance [CrCl] 15 to 30 ml/min per 1.73 m(2)) and serum bicarbonate 16 to 20 mmol/L to either supplementation with oral sodium bicarbonate or standard care for 2 yr. The primary end points were rate of CrCl decline, the proportion of patients with rapid decline of CrCl (>3 ml/min per 1.73 m(2)/yr), and ESRD (CrCl <10 ml/min). Secondary end points were dietary protein intake, normalized protein nitrogen appearance, serum albumin, and mid-arm muscle circumference. Compared with the control group, decline in CrCl was slower with bicarbonate supplementation (5.93 versus 1.88 ml/min 1.73 m(2); P < 0.0001). Patients supplemented with bicarbonate were significantly less likely to experience rapid progression (9 versus 45%; relative risk 0.15; 95% confidence interval 0.06 to 0.40; P < 0.0001). Similarly, fewer patients supplemented with bicarbonate developed ESRD (6.5 versus 33%; relative risk 0.13; 95% confidence interval 0.04 to 0.40; P < 0.001). Nutritional parameters improved significantly with bicarbonate supplementation, which was well tolerated. This study demonstrates that bicarbonate supplementation slows the rate of progression of renal failure to ESRD and improves nutritional status among patients with CKD.

Figure 1.

Participant enrollment and randomization to the study. Arm A (left column) allocated to oral bicarbonate and arm B (right colum) allocated to standard therapy.

Figure 2.

(A) Plasma HCO₃⁻ levels during the study period. Squares and bars denote means and SD. (B) Urinary sodium (Na) excretion per day. Squares and bars denote means and SD. (C) BP control during the study period. Squares and bars denote means and SD. (D) Urinary total protein excretion per day during the study period. Squares and bars denote means and SD. (E) Rate of decline of CrCl. Squares and bars denote means and SD.

Figure 3.

Kaplan-Meier analysis to assess the probability of reaching ESRD for the two groups.

Figure 4.

(A) Dietary protein intake on 4-d patient dietary records. Data are means and SD. (B) nPNA during the study period. Data are means and SD. (C) MAMC measurements during the study period. Data are means and SD. (D) Plasma albumin levels in the control and bicarbonate groups during the study period. Data are means and SD. (E) Serum potassium levels in the control and bicarbonate groups during the study period. Data are means and SD.