Laboratory Hemostasis: A Practical Guide for Pathologists

By Sterling T. Bennett, Christopher M. Lehman and George M. Rodgers

Coagulation testing is the basis for the diagnosis of bleeding and thrombotic disorders, as well as the mainstay of anticoagulant monitoring and management. This handbook provides practical information and guidance on topics relevant to directing a coagulation laboratory, filling a void in the literature. Since the first edition, all chapters have been updated and an entirely new chapter is included on pharmacogenomics and pharmacogenetics. The book will aid pathologists, clinical laboratory scientists and other physicians serving as laboratory directors to understand and carry out their responsibilities. It will also assist residents and fellows in learning the basics of coagulation testing and serve as a useful day-to-day reference for coagulation laboratory supervisors, technologists, and technicians. Finally, clinicians may find aspects of the book helpful in understanding the role of the coagulation laboratory in patient evaluation and monitoring.

• Language: English
• Publisher: Springer
• Release date: Oct 14, 2014
• ISBN: 9783319089249

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© Springer International Publishing Switzerland 2015

Sterling T. Bennett, Christopher M. Lehman and George M. RodgersLaboratory Hemostasis10.1007/978-3-319-08924-9_2

2. Collection of Coagulation Specimens

Sterling T. Bennett¹, ², ³  

(1)

Pathology Department, Intermountain Healthcare Urban Central Region, Salt Lake City, UT, USA

(2)

Pathology Department, University of Utah Health Sciences Center, Salt Lake City, UT, USA

(3)

Intermountain Healthcare Central Laboratory, Salt Lake City, UT, USA

Sterling T. Bennett

Email: [e-mail]

2.1 Collection of Specimens for Hemostasis Testing

Specimen integrity is important for every laboratory test, but especially for coagulation testing, where even minor deviations from standard practices may lead to inaccurate results. Citrated plasma is the most common specimen type for routine and special coagulation testing, and the suitability of citrated plasma is particularly sensitive to anticoagulant concentration, container materials, collection technique, centrifugation, and storage. Accordingly, this chapter will emphasize citrated plasma specimens, but will also address other specimen types that are becoming increasingly important in hemostasis testing. The purpose of this chapter is to describe current recommendations for and points of ambiguity about specimens for hemostasis testing to assist the laboratory director in establishing standard operating procedures and evaluating the acceptability of non-ideal specimens.

2.2 Citrate Anticoagulant Concentration

The recommended anticoagulant for coagulation specimens is 105–109 mmol/L (3.13–3.2 %) trisodium citrate (Na3C6H5O7 · 2H2O), commonly called 3.2 % citrate, with or without buffer [1]. A higher concentration of citrate (129 mmol/L or 3.8 %) is also commercially available and is considered acceptable by the Clinical and Laboratory Standards Institute (CLSI), but has some important disadvantages, including producing longer prothrombin time (PT) and partial thromboplastin time (PTT) results [2], lower activated protein C (APC) resistance results [3], and discrepant International Normalized Ratio (INR) values [4, 5]. Furthermore, thromboplastin International Sensitivity Index (ISI) values for calculating INRs are assigned using specimens collected in 3.2 % citrate, based on the World Health Organization protocol, and are not validated for specimens collected in 3.8 % citrate [5]. Laboratories should not use 3.2 and 3.8 % citrate interchangeably. Other citrate formulations are commercially available and CLSI considers them to be acceptable for some assays, but if used for routine coagulation testing, then anticoagulant-specific reference intervals should be