Spuriously low immunosuppressant results due to incomplete hemolysis – A pitfall in transplant patient therapeutic drug monitoring

Therapeutic drug monitoring (TDM) plays a crucial role in transplantation medicine when it comes to immunosuppressants like Tacrolimus, Cyclosporine A, Sirolimus, and Everolimus. The analysis involves using immunometric or mass spectrometric methods on whole blood samples. Hemolysis of the samples is necessary for the assessment. Typically, this is accomplished through manual protein precipitation using pre-treatment reagents, followed by vigorous vortex mixing and subsequent centrifugation. It is important to note that omitting the vortex step in these manual procedures can be seen as a potential procedural error.