Acetate metabolism during hemodialysis

Area of Science:

• Nephrology
• Biochemistry
• Physiology

Background:

• Acetate is commonly used in hemodialysis for buffering.
• Previous studies suggested zero-order acetate metabolism during dialysis.
• The metabolic fate of acetate during dialysis requires further kinetic investigation.

Purpose of the Study:

• To investigate the kinetics of acetate metabolism in normal subjects and dialysis patients.
• To determine if acetate metabolism during dialysis follows zero-order or Michaelis-Menten kinetics.
• To correlate acetate metabolism capacity with acid-base balance during hemodialysis.

Main Methods:

• Kinetic analysis of plasma and urine acetate levels in normal subjects during acetate infusion.
• Kinetic modeling of acetate concentrations during hemodialysis using a Michaelis-Menten model.
• Correlation analysis between maximal metabolic rate (Vmax) and plasma bicarbonate changes.

Main Results:

• Acetate elimination in normal subjects followed first-order kinetics (clearance rate 2.3 L/min).
• Acetate metabolism in dialysis patients best fitted a Michaelis-Menten model (Km 8.5 mM, Vmax 18 mmol/min).
• Low Vmax (< 7 mmol/min) correlated with decreased plasma bicarbonate, while high Vmax (> 14 mmol/min) correlated with increased bicarbonate.

Conclusions:

• Acetate metabolism capacity significantly impacts acid-base homeostasis during high-surface-area dialysis.
• Kinetic modeling can identify "acetate-intolerant" patients.
• This approach may predict patients who would benefit from bicarbonate hemodialysis.