An investigation of enzymatic creatinine interference in a patient receiving dopamine and dobutamine

Abstract

BackgroundA laboratory investigation was initiated after a renal failure patient had a 2.18 mg/dL decrease in serum creatinine, which was not explained through medical intervention. The investigation revealed specimens providing questionably low results had been collected from a peripherally inserted central catheter (PICC) line. MethodsPatient specimens and serum pools were analyzed by the Siemens Vista enzymatic creatinine measurement procedure. A simulation of the patient's infusion protocol examined potential PICC line carryover and specimen collection technique. ResultsA simultaneously collected specimen set, arterial line and PICC line, yielded a difference of 1.86 mg/dL. Infusion and collection simulation studies suggested the most likely scenario was the infusion pump was not shut off while the specimen collection occurred and contaminated the specimen. ConclusionProviders should be aware of erroneously low creatinine results when administering catecholamine drugs and collecting specimens through the same catheter. The mechanism of specimen contamination is consistent with a siphoning effect from one lumen to the other during collection with the infusion pumps still running.