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Reviews: Lori J. Sokoll, Frank H. Wians, Jr, and Alan T. Remaley Rapid Intraoperative Immunoassay of Parathyroid Hormone and Other Hormones: A New Paradigm for Point-of-Care Testing Clin Chem 2004; 50: 1126-1135 [Abstract] [Full text] [PDF]

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High-speed centrifugation of primary EDTA tubes improves turn-around time in the central laboratory

Markus Roser, Helma Preez, Ulrich Sill, Matthias Nauck   (5 October 2004)

High-speed centrifugation of primary EDTA tubes improves turn-around time in the central laboratory 5 October 2004
Markus Roser, M.D. University Hospital Greifswald, Helma Preez, Ulrich Sill, Matthias Nauck Send letter to journal: Re: High-speed centrifugation of primary EDTA tubes improves turn-around time in the central laboratory markus.roser{at}uni-greifswald.de Markus Roser, et al.	To the Editor: In the July issue of Clinical Chemistry, Sokoll et al. gave an excellent overview on rapid intraoperative immunoassays, with the focus on parathyroid hormone (PTH) (1). The five PTH assays listed by the authors are all approved for use with serum and EDTA plasma. It should be emphasized that EDTA plasma is the specimen of choice for intraoperative PTH testing, to avoid analytical problems due to clotting. Despite the main advantage of point-of-care assays, reduced turn- around time, the majority of institutions perform intraoperative PTH analyses in the central laboratory (2). We agree with Sokoll et al. that the time of transport is a major aspect of turn-around time, but centrifugation is another one. With POCT assays, blood is transferred from the primary tube to a small sample cup and centrifuged for 30 seconds in a microcentrifuge. In contrast, standard centrifugation times in many laboratories are 10 (5 to 15) minutes at a relative centrifugal force of 1000 – 1100 g (3). In recent years, small high-speed centrifuges have become available, which reduce the time needed to prepare serum or plasma from standard blood sampling tubes to less than 3 minutes without the need to transfer the blood to a sample cup. These centrifuges have been introduced for a variety of different urgent laboratory tests (4). In our hospital, intraoperative PTH assays are performed in the central laboratory with the Turbo Intact PTH assay on an Immulite instrument (DPC Biermann, Bad Nauheim, Germany). Blood is collected in K2 EDTA tubes (Becton Dickinson, Heidelberg, Germany, art. no. 368841). With introduction of a high-speed centrifuge which allows centrifugation of primary tubes in 120 seconds at 4440g (StatSpin Express2, IRIS International Inc., Norwood, MA) we were able to improve our turn-around time for intraoperative PTH measurements by at least 10 minutes to an average of 32 minutes. References 1. Sokoll LJ, Wians FH, Remaley AT. Rapid intraoperative immunoassay of parathyroid hormone and other hormones: a new paradigm for point-of- care testing [Review]. Clin Chem 2004;50:1126-35. 2. Hortin GL, Carter AB. Intraoperative parathyroid testing: survey of testing program characteristics. Arch Pathol Lab Med 2002;126:1045-9. 3. NCCLS. Procedures for the handling and processing of blood specimens; approved guideline, 2nd ed. Wayne: NCCLS document H18-A2, 1999. 4. Foster K, Datta P, Orswell M, Tasaico K, Alpert A, Bluestein B. Evaluation of a centrifuge with rapid turnaround time for the preparation of plasma samples for measurement of common STAT markers on the ACS: 180 system. Clin Lab. 2000;46:157-60.