Abstract: SA-PO1128
Sampling Site Matters: A Falsely Elevated Tacrolimus Level After Stopping IV Infusion in a Patient with Central Venous Catheters
Session Information
- Transplant Trainee Case Reports
November 09, 2019 | Location: Exhibit Hall, Walter E. Washington Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Trainee Case Report
- 1902 Transplantation: Clinical
Authors
- Kadhem, Salam, University of Florida, Gainesville, Florida, United States
- Al-Ani, Israa, University of Florida, Gainesville, Florida, United States
- Alquadan, Kawther Farouk, Shands Hospital/University of Florida, Gainesville, Florida, United States
Introduction
Tacrolimus levels abnormalities constitute a major concern to transplant nephrologists. Based on these values; decisions are made to adjust Tacrolimus doses to achieve adequate immunosuppression. The recognition of pitfalls with these laboratory tests becomes crucial to better interpret the accuracy of these results, specifically when dealing with critically ill patients using intravenous Tacrolimus where a large subset of these patients have central venous catheters that are used for infusions and blood sampling. We are reporting a case of falsely elevated Tacrolimus levels after discontinuation of the medication.
Case Description
A 52-year-old male with history of gastroparesis and kidney transplantation in 2011, presented with sever nausea, vomiting and inability to tolerate oral intake including his oral tacrolimus for one day prior to admission. On presentation, his Tacrolimus level was 3.1 ng/mL. Intravenous continuous infusion of Tacrolimus was initiated via a PICC line. Two days later, his symptoms have resolved and subsequently transitioned back to oral Tacrolimus. Next day Tacrolimus trough (drawn from the PICC line after multiple flushes) came back at 38.9 ng/mL, repeated level confirmed to be more than 30 ng/mL. Immediately, his oral tacrolimus was held. Interestingly, he did not exhibit any signs or symptoms of tacrolimus toxicity and his renal function remained stable at baseline. Rechecked daily troughs for the next 3 days were 23, 17 and 19 ng/mL, despite holding tacrolimus. Simultaneous samples were drawn from both PICC line and peripheral vein showed great discrepancy with troughs of 39.0 ng/mL and less than 3.0 ng/mL respectively. Historically, a similar misinterpretation occurred which led to prolonged hospital stay with potential compromise to his immunosuppression.
Discussion
Falsely elevated Tacrolimus levels in samples drawn from central venous catheters have been reported to last several days despite rinsing the catheter. Studies have shown evidence of reversible adsorption of the drug from the inner walls of different catheters.
Raising awareness to this misleading phenomenon helps avoiding dangerous dose reductions of the immunosuppressive drug and unnecessarily prolonged hospital stay. Sampling for Tacrolimus level should always be drawn from peripheral veins.