(P-PB-17) Impact of RBC Transfusions on Phosphatidylethanol (PEth) Levels

Phosphatidylethanol (PEth), is a long-term biomarker in the phospholipid membrane of red blood cells (RBC) for alcohol consumption, crucial in clinical assessments like liver pre-transplant candidacy. PEth has a window of detection of 2-4 weeks, however, the window is longer in people who chronically or excessively consume alcohol. We present a case review of a recipient’s PEth results during serial RBC transfusions, demonstrating that RBC transfusion can both increase and decrease PEth concentrations, and that a single RBC unit can be sufficient to substantially alter recipient PEth concentrations.

Study

Design/Methods:

This study was conducted using liquid chromatography – tandem mass spectrometry method to analyze the predominant form used in clinical guidelines, POPEth, levels in EDTA whole blood samples collected on study patient & citrated RBC donor segments. The validated lower limit of POPeth quantitation is 10 ng/mL. The patient was admitted, therefore, no alcohol was consumed during the study period.

Results/Findings:

The patient’s PEth concentration was < 10 ng/mL prior to transfusion.  Massive blood transfusion (MBT) was initiated for hematochezia, in which they received 7 RBCs. Donor segments from the MBT were not available for PEth testing, but the patient’s post-MBT PEth was 28 ng/mL.

Over the next 24 hours, they received 8 more RBCs until bleeding stabilized. Donor segment PEth levels ranged from undetectable to 161 ng/mL. Patient PEth remained stable after 2 additional RBCs despite moderately high PEth concentrations in those units, reflecting the patient’s actively bleeding and ongoing loss of both existing and newly-transfused RBCs during endoscopy to control the bleeding. Patient PEth gradually declined to < 10 ng/mL with transfusion of 5 RBC units (primarily PEth of < 10 ng/mL). One final RBC unit (PEth of 128ng/mL) caused elevation to 18 ng/mL in patient (Figure A).

Conclusions:

This case emphasizes the importance of recognizing that RBC transfusions can artificially affect PEth results, with even a single unit causing significant changes. Careful consideration is needed to avoid misinterpretation of PEth results, given the potential for both elevation and reduction after recent RBC transfusion. Units with PEth < 10 ng/mL led to decreasing PEth concentrations in the recipient, while a single unit of high PEth was sufficient to elevate the patient’s blood PEth from undetectable to detectable.

The prevalence of PEth in blood donors poses challenges in assessing alcohol use in patients who are frequent RBC recipients. Collaboration between transplant centers, clinical specialties such as behavior medicine, and transfusion medicine services is vital to establish testing protocols and interpret PEth levels accurately in recipients.