Evaluation of test strips for the rapid identification of ethylenediaminetetraacetic acid (EDTA) specimens.
BACKGROUND
Identification of specimens that contain ethylenediaminetetraacetic acid (EDTA) is frequently necessary when investigating potentially mislabeled or improperly collected specimens.


OBJECTIVE
To evaluate the performance of rapid EDTA detection test strips in clinical specimens.


METHODS
We applied specimens to test strips designed to detect EDTA (QUANTOFIX EDTA) using a pipet (drop mode). Reactions were scored visually on a scale from red (no EDTA) to orange (low/indeterminate EDTA) to yellow (contains EDTA).


RESULTS
Test strips reliably identified specimens from EDTA-containing tube types. Although test strips did not detect strong reactivity in other specimens, tubes containing NaFl/K-oxalate produced an orange (low/indeterminate EDTA) reaction. Bismuth and citrate levels were higher in specimens after we dipped test strips into solution (dip mode).


CONCLUSIONS
Test strips detected the presence of EDTA in concentrations found in EDTA-containing primary tubes. Test strips were less effective in evaluating low-level EDTA concentrations expected with intravenous line contamination or backflow. Indeterminate reactions required further investigation. Dip mode can produce analytical problems for assays that measure (or are interfered by) the contents of test strips.
ARUP Laboratories, Salt Lake City, Utah.
Kelly L
KL
Scholes
ARUP Institute for Clinical and Experimental Pathology, Salt Lake City, Utah.
Sonia L
SL
La'ulu
ARUP Laboratories, Salt Lake City, Utah.
Ammon T
AT
Ence
ARUP Laboratories, Salt Lake City, Utah.
Heather L
HL
Logan
ARUP Laboratories, Salt Lake City, Utah.
Rebecca L
RL
Parker
ARUP Laboratories, Salt Lake City, Utah ARUP Institute for Clinical and Experimental Pathology, Salt Lake City, Utah Department of Pathology, University of Utah, Salt Lake City, UT.
Frederick G
FG
Strathmann
ARUP Laboratories, Salt Lake City, Utah ARUP Institute for Clinical and Experimental Pathology, Salt Lake City, Utah Department of Pathology, University of Utah, Salt Lake City, UT jonathan.genzen@path.utah.edu.
Jonathan R
JR
Genzen
D001800:Blood Specimen Collection; D004492:Edetic Acid / Q000097:blood* / Q000737:chemistry; D005189:False Positive Reactions; D006801:Humans; D016014:Linear Models; D011934:Reagent Strips; D015203:Reproducibility of Results
D011934:Reagent Strips; D004492:Edetic Acid
EDTA; aliquot; mislabeled specimen; phlebotomy; plasma; serum; test strip