Fluctuating creatinine in the cardiac unit

Athena K Petrides; Mary Ann Ness; Daniel P Judge; Lori J Sokoll; Mark A Marzinke

doi:10.1016/j.cca.2015.05.012

Fluctuating creatinine in the cardiac unit

Clin Chim Acta. 2015 Jul 20;447:52-4. doi: 10.1016/j.cca.2015.05.012. Epub 2015 May 23.

Authors

Athena K Petrides¹, Mary Ann Ness², Daniel P Judge³, Lori J Sokoll¹, Mark A Marzinke⁴

Affiliations

¹ Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
² Johns Hopkins Medical Institutions, Johns Hopkins Hospital, Baltimore, MD, USA.
³ Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
⁴ Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA. Electronic address: mmarzin1@jhmi.edu.

PMID: 26014810
DOI: 10.1016/j.cca.2015.05.012

Abstract

Background: Inconsistent serum creatinine results were observed in a patient with a history of λ light-chain (AL) amyloidosis with multiple comorbidities, including renal nephropathy. Throughout admission, serum creatinine concentrations varied and were inconsistent with the patient's clinical presentation. Studies were conducted to elucidate the cause of the observed fluctuations.

Methods: Whole blood plasma and serum samples were assessed using alternate methodologies and confirmed a falsely low creatinine concentration when analyzed using an enzymatic methodology. A review of the patient's chart identified a potential interfering substance, which was verified via spiking studies. A review of the specimen collection practices was also conducted to understand the intermittently low creatinine values.

Results: Upon admission, the patient's serum creatinine concentration was 1.7mg/dl. However, creatinine values varied from 0.6 to 1.9mg/dl in the proceeding days, and the low creatinine concentrations were inconsistent with the patient's clinical presentation. To investigate, paired specimens were collected for whole blood plasma analysis via amperometric detection and serum analysis using either enzymatic or Jaffe methodologies. Enzymatic measurement of creatinine resulted in a lower creatinine concentration (0.6mg/dl) as compared to kinetic Jaffe or whole blood testing (1.8mg/dl). Following consultation with the clinical team, the patient had been administered dopamine intravenously in the days following admission. Studies illustrated dopamine concentrations above 6.50×10(5)pg/ml resulted in decreased creatinine concentrations when measured enzymatically. The intermittent low creatinine concentrations observed were due to collection via a peripherally inserted central catheter line.

Conclusion: Fluctuations in serum creatinine concentrations in a hospitalized patient were due to interference by dopamine. Samples collected from a peripherally inserted central catheter line in which dopamine was administered resulted in the suppression of peroxidase assays that use phenazone as a substrate.

Keywords: Creatinine; Dopamine; Enzymatic assay; Interference; Preanalytical variables.

Publication types

Case Reports

MeSH terms

Amyloidosis / blood
Amyloidosis / complications
Cardiology*
Creatinine / blood*
Dopamine / administration & dosage
Dopamine / pharmacology
False Negative Reactions
Female
Hospitalization
Humans
Middle Aged

Substances

Creatinine
Dopamine