Amino acid balance with extended daily diafiltration in acute kidney injury

Background: The impact of hybrid dialysis therapies on amino acid (AA) balance in critically ill patients with acute kidney injury is unknown. Methods: We examined prospectively the AA balance with extended daily diafiltration (EDDF). Results: We studied 7 patients. AA clearances with EDDF ranged from 21.6 ml/min (tryptophan) to 66.9 ml/min (taurine). AA loss was 4.2 (IQR 1.4–12.3) g/day and 4.5% of daily protein intake for patients on enteral nutrition (EN). Percentage AA loss per hour on EDDF was highest for glutamine (32.1%) and lowest for glutamic acid (0.8%). Blood AA levels correlated with corresponding EDDF losses. Median total nitrogen appearance was 25.0 (IQR 20.6–29.3) g/day for patients on EN. This resulted in a negative nitrogen balance of –10.7 (IQR –16.6 to –1.4) g/day, of which 6.5% was attributable to AA loss. Conclusions: AA loss with EDDF was limited, but with much individual variability, and contributed to a strongly negative daily nitrogen balance.