Monitoring of cyclosporine levels in transplant recipients using self-administered fingerprick sampling

Use of C-2 monitoring for cyclosporine A (CsA) microemulsion results in improved clinical outcomes vs. trough (C-0) monitoring. Logistical issues include accurate timing of the C-2 sample; requirement for sample dilution with most standard assay techniques; and inconvenience for patients. Recently, it has been shown that CsA concentrations in capillary blood correlate closely with levels in venepuncture samples, and that liquid chromatography tandem mass spectrometry (LC-MS/MS) can analyse CsA concentration using undiluted capillary blood from fingerprick samples. In a study to assess the feasibility of CsA monitoring, 52 stable heart transplant patients were provided with kits to take fingerprick trough and C-2 blood samples at home, returning them to the laboratory by post for LC-MS/MS analysis. In total, 225 samples were provided, of which 14 (6%) were unsuitable for analysis because of clotting (n=10) or insufficient volume (n=4). Discomfort was not a problem and initial difficulties that some patients reported in taking the samples resolved with experience. All samples were returned by the postal system in a timely manner. Use of fingerprick assays could allow transplant physicians to have access to C-2 levels when patients visit the clinic for review, and avoids the need for patients to attend the clinic or local healthcare centre solely for venepuncture. A barrier to more widespread introduction of fingerprick testing is likely to be lack of suitable MS facilities and trained personnel. In conclusion, self-administered fingerprick testing for CsA blood levels is practical to implement and highly convenient for patients and offers advantages for the transplant team.