Artificially Elevated Tacrolimus Concentrations Obtained From a Venous Catheter Previously Used for Tacrolimus Administration in a Pediatric Patient.

Intravenous (IV) administration of calcineurin inhibitors, cyclosporine (CsA) and tacrolimus (TAC), has been associated with spuriously high serum concentrations collected from central venous catheters (CVCs) used for medication administration, secondary to reversible adsorption of medication to the catheter. Thus, therapeutic drug monitoring of IV CsA and TAC via CVCs previously exposed to these agents should be interpreted cautiously and ideally avoided. The duration of this effect is poorly characterized and the risk for extension of this effect to unexposed lumens of the same central catheter remains uncertain. We describe a case of a pediatric patient with artificially elevated serum TAC concentrations obtained from previously exposed and unexposed lumens of a central catheter, 27 days after last IV TAC administration.