Capillary blood stability and analytical accuracy of 12 analytes stored in Microtainers®.
Author(s): Fontaine E, Saez C
Publication: Pract Lab Med, 2023, Vol. 36, Page e00325
PubMed ID: 37649539 PubMed Review Paper? No
Purpose of Paper
This paper compared the stability of 12 clinical chemistry analytes in paired venous specimens that were shipped on wet ice and capillary specimens (collected into a microcontainer) that were shipped at ambient temperature.
Conclusion of Paper
The majority of the analytes evaluated demonstrated a strong correlation between the two types of venous specimens, which was greater than 97%. For all analytes evaluated, the correlation plots were considered statistically identical (slope of 1 and intercept of 0 within the 95% confidence interval). The negative predictive value of the microtainer capillary specimens was 100% for all analytes except triglycerides, which led the authors to conclude that collection and shipping methods can be considered equivalent. Relative to matched venous specimens, the degree of bias observed in the microtainer capillary specimens was small for most analytes, with few specimens (0-4) exceeding the allowable error specified. However, aspartate aminotransferase (AST) had a bias of 40%, and AST levels in 26 of 31 microtainer capillary specimens exceeded the allowable error.
Studies
-
Study Purpose
This study compared the stability of 12 clinical chemistry analytes in paired venous specimens that were shipped on ice and capillary specimens that were shipped at ambient temperature. Blood from 31 healthy volunteers was first collected by venipuncture into serum separator and EDTA vacutainer tubes and then by fingerstick with a contact-activated lancet into lithium heparin microtainers. Serum separator tubes were centrifuged at 2000 g for 15 min. Serum and EDTA Vacutainer tubes were placed in Styrofoam containers with cold packs (mean temperature was 12.9°C; range 11.3-17.1°C) and transported to the laboratory. Upon arrival, the caps of venous specimens were removed, and tubes were loaded into the analyzer. Microtainers containing capillary specimens were inverted 10 times and then transported without refrigeration (mean 24.8°C; range 19.6-28.5°C). Upon arrival, microtainers were mixed and hemoglobin A1c was measured in an aliquot before separation of plasma by centrifugation at 3,000 g for 5 min. Levels of hemoglobin A1c (HbA1c), total cholesterol, triglycerides, high-density lipoprotein cholesterol, creatinine, urea nitrogen, uric acid, alkaline phosphatase (ALP), alanine transaminase (ALT), AST, gamma-glutamyl transferase, and total protein were quantified using a Roche c502 COBAS 8000 modular platform.
Summary of Findings:
The majority of the analytes evaluated demonstrated a strong correlation (>97%) between venous specimens shipped on wet ice and capillary specimens shipped at ambient temperatures, meeting the authors’ criterion for a good association. However, the strength of the correlation between specimen types for uric acid and total protein was slightly lower (0.9240 and 0.7813, respectively). For uric acid and total protein, the correlation plot of the two collection and shipment methods had a slope of 1 and an intercept of 0 that fell within the 95% confidence interval, and, as such, the methods were statistically identical. The medical decision point for the microtainer capillary specimen was set based on the 95% confidence interval for the venous specimen and was not within range for high-density lipoprotein cholesterol, uric acid, and liver enzymes (total protein excluded due to a correlation that was <90%). Based on results obtained with venous specimens, the bias associated with microtainer capillary specimens was 0.7-11% for most analytes, with the exception of AST which had a bias of 40%. However, in all cases, the bias was not systematic and outliers were present in each direction. For most analytes, only a small number (0-4 of 31) of capillary specimens in microtainers fell outside the allowable error, but for AST 26 of 31 specimens fell outside the allowable error. Finally, the negative predictive value for the microtainer capillary specimens was 100% for all analytes with the exception of triglycerides, which led the authors to conclude that both methods could be considered equivalent.
Biospecimens
Preservative Types
- None (Fresh)
Diagnoses:
- Normal
Platform:
Analyte Technology Platform Lipid Clinical chemistry/auto analyzer Steroid Clinical chemistry/auto analyzer Small molecule Clinical chemistry/auto analyzer Protein Clinical chemistry/auto analyzer Pre-analytical Factors:
Classification Pre-analytical Factor Value(s) Biospecimen Acquisition Type of collection container/solution Vacutainer tube
Microtainer
Biospecimen Aliquots and Components Centrifugation Centrifugation delays investigated
Storage Specimen transport duration/condition On ice
Ambient temperature
Biospecimen Acquisition Method of fluid acquisition Venipuncture
Finger/heel prick sampling