Clot activators and anticoagulant additives for blood collection. A critical review on behalf of COLABIOCLI WG-PRE-LATAM

Abstract

In the clinical laboratory, knowledge of and the correct use of clot activators and anticoagulant additives are critical to preserve and maintain samples in optimal conditions prior to analysis. In 2017, the Latin America Confederation of Clinical Biochemistry (COLABIOCLI) commissioned the Latin American Working Group for Preanalytical Phase (WG-PRE-LATAM) to study preanalytical variability and establish guidelines for preanalytical procedures to be applied by clinical laboratories and health care professionals. The aim of this critical review, on behalf of COLABIOCLI WG-PRE-LATAM, is to provide information to understand the mechanisms of the interactions and reactions that occur between blood and clot activators and anticoagulant additives inside evacuated tubes used for laboratory testing. Clot activators – glass, silica, kaolin, bentonite, and diatomaceous earth – work by surface dependent mechanism whereas extrinsic biomolecules – thrombin, snake venoms, ellagic acid, and thromboplastin - start in vitro coagulation when added to blood. Few manufacturers of evacuated tubes state the type and concentration of clot activators used in their products. With respect to anticoagulant additives, sodium citrate and oxalate complex free calcium and ethylenediaminetetraacetic acid chelates calcium. Heparin potentiates antithrombin and hirudin binds to active thrombin, inactivating the thrombin irreversibly. Blood collection tubes have improved continually over the years, from the glass tubes containing clot activators or anticoagulant additives that were prepared by laboratory personnel to the current standardized evacuated systems that permit more precise blood/additive ratios. Each clot activator and anticoagulant additive demonstrates specific functionality, and both manufacturers of tubes and laboratory professional strive to provide suitable interference-free sample matrices for laboratory testing. Both manufacturers of in vitro diagnostic devices and laboratory professionals need to understand all aspects of venous blood sampling so that they do not underestimate the impact of tube additives on laboratory testing.

Keywords:

• Blood specimen collection
• patient safety
• phlebotomy
• tube additive
• anticoagulant
• clot activator

Acknowledgements

Our special thanks to Prof. Bill Rankin for authorizing the use and adaptation of his graph previously published at http://www.radicalcartography.net/index.html?howhigh (our Figure 5). Our sincere thanks to our friends, Waldemar Volanski, PhD, for drawing the Figures 2 and 3; Rafael Viana da Silva, D.Chem, for drawing Figures 4 and 6–8; and Mr. Julys Palmeira for drawing Figure 9. This critical review concludes the project ADR 2451/15.

Disclosure statement

No potential conflict of interest was reported by the author(s).