The Association Between Tacrolimus Levels and Hyperkalemia in Allograft Recipients Who Underwent Heart or Lung Transplantation in New Orleans, USA Between 2013 and 2019: A Single-Center Retrospective Study

BACKGROUND: Tacrolimus, a calcineurin inhibitor, is the cornerstone of immunosuppressive strategies in transplantation. Other studies have concluded that hyperkalemia correlates with tacrolimus therapy, though the impact is poorly understood. In 2 separate analyses, the aim of this study was to investigate if the presence and/or magnitude of exposure to tacrolimus increased potassium levels in heart or lung transplant recipients. MATERIAL/METHODS: This retrospective study identified allograft recipients who underwent heart or lung transplantation from January 2013 to December 2019 at Ochsner Health in New Orleans, USA. The first analysis (A-1) comprised 103 lung transplant patients’ assessed potassium levels and prevalence of hyperkalemia in the absence of tacrolimus before transplant versus 30 days after transplant on tacrolimus. The second analysis (A-2) included 187 heart or lung transplant recipients and compared potassium levels and prevalence of hyperkalemia at day 30 after transplant during higher tacrolimus exposure (High-TAC) vs day 300 during lower tacrolimus exposure (Low-TAC). RESULTS: In A-1, patients on tacrolimus had higher median potassium (4.7 mmol/L vs 4.1 mmol/L, P<0.0001) and prevalence of hyperkalemia (32.04% vs 5.83%, P<0.0001). In A-2, patients in the High-TAC group had higher median potassium (4.6 mmol/L vs 4.4 mmol/L, P=0.0005) and prevalence of hyperkalemia (22.46% vs 12.30%, P=0.0056). CONCLUSIONS: Our findings support those from previous studies. Presence of and higher levels of tacrolimus were associated with hyperkalemia following heart and lung transplantation. These findings highlight the importance of long-term monitoring of potassium levels in patients treated with tacrolimus.