Phosphatidylethanol clearance after packed red blood cell transfusion

Phosphatidylethanol (PEth) is a long-term marker of alcohol consumption used clinically for evaluating abstinence in patients including transplant candidates. Packed red blood cell (pRBC) transfusion can introduce exogenous PEth to recipients, complicating interpretation. This study evaluated the kinetics and duration of PEth 16:0/18:1 positivity post-transfusion.

This study evaluated liver transplant recipients (n = 76) who received ≥ 1 pRBC during transplantation surgery. PEth 16:0/18:1 concentrations were monitored up to 2 weeks post-transfusion to determine clearance kinetics.

Post-transfusion PEth was ≥ 10 ng/mL (range 10.0 - 79.7 ng/mL [0.014-0.113 µmol/L]) in 37 (48.7 %) recipients. Approximately 24 h after transfusion, pRBC-derived PEth decreased by a mean of 19 %, consistent with pRBC turnover post-transfusion. After 24-36 h, the apparent half-life of PEth was 6.6 d but was highly variable (SD 3.6 d). Correction for hemoglobin or hematocrit improved variability, with mean half-life estimated at 4.9 d (SD 1.6 d) and 4.6 d (SD 1.4 d), respectively. Time to clearance of PEth < 10 ng/mL ([<0.014 µmol/L]) ranged from < 1 d to > 19 d; 15 (40.5 %) pRBC recipients cleared PEth within 5 d post-transfusion. Using the consensus cutoff for PEth interpretation, only 10 had PEth > 20 ng/mL (>0.028 µmol/L) at 5 d and all had 14 d values < 20 ng/mL (<0.028 µmol/L).

These findings suggest that PEth positivity after pRBC transfusion might be more common than previously recognized, and that higher decision-making thresholds (e.g., 20 ng/mL [<0.028 µmol/L]) are appropriate. Post-transfusion kinetics are not identical to clearance of endogenously-produced PEth after alcohol consumption (half-life 5-8 d), likely due to both patient and pRBC characteristics. Transplant care teams should recognize the risk for pRBC transfusion to impact PEth concentrations in recipients, and interpret PEth cautiously for 2-3 weeks after transfusion.