Nutritional effects of delivered bicarbonate dose in maintenance hemodialysis patients.

OBJECTIVE: Metabolic acidosis is common in patients with end-stage renal disease (ESRD). Studies suggest that correction of acidosis may improve nutritional status and patient outcomes. The purpose of this study was to examine the effects of increasing delivered bicarbonate dose from 35 mmol/L to 39 mmol/L with respect to nutrition-related outcomes in maintenance hemodialysis patients (MHD).

DESIGN AND SETTING: This was a longitudinal, observational study conducted at 4 dialysis centers in western Massachusetts. Patients were followed for 6 months after change in bicarbonate dose protocol.

PATIENTS: The study sample consisted of 248 patients who had been on MHD for at least 1 year on the standard bicarbonate dialysate of 35 mmol/L without oral bicarbonate supplements.

MAIN OUTCOME MEASURES: Measures of interest included predialysis serum bicarbonate, albumin, hemoglobin, potassium, phosphorus, calcium, and parathyroid hormone (iPTH), as well as protein catabolic rate (nPCR). A subset of patients (n = 35) was examined for changes via Subjective Global Assessment (SGA).

RESULTS: Serum bicarbonate improved significantly from baseline (21.7 +/- 2.8 mmol/L; mean +/- SD) at 3 months (23.3 +/- 3.3) and 6 months (23.1 +/- 3.3) (P <.0001). Phosphorus decreased from 6.0 +/- 2.0 mmol/L at baseline to 5.7 +/- 1.7 mmol/L (P =.02) at 6 months, although calcium, iPTH, and potassium remained relatively stable. Serum bicarbonate was inversely and significantly correlated with nPCR at baseline (r = -0.23; P <.05) and 3 months (r = -0.22; P <.05). The nPCR decreased significantly (P =.001) from baseline (0.99 +/- 0.26) at 6 months (0.93 +/- 0.23), whereas the serum albumin and SGA scores did not differ.

CONCLUSION: Increasing delivered bicarbonate dose improves serum bicarbonate and may decrease catabolism. Further study is needed to confirm the potential nutritional benefits.