Heparinase

Margaret Peters, MD at MHS Health asks:

What coagulation tests may be run on samples previously treated with heparinase? Is any correction factor required for a quantitative assay? Are there any published guidelines on this topic? Thank you!

Hello, Dr. Peters. Heparinase is manufactured by Ibex and distributed by Siemens Laboratory Diagnostics, Inc. as Hepzyme. It specifically digests heparin, yielding oligosaccharides, and it does not interact with proteins. I checked with Dave McGlasson at Wilford Hall Hospital in San Antonio, who had worked extensively with heparinase, and he provided the following detailed information (thanks, Dave for your detail):

Actually I knew Dr. Peters when she was a pathology resident.  To my knowledge there are no interference issues with heparinase I, which is manufactured by IBEX.  It is primarily used to neutralize both unfractionated and low molecular weight heparin to remove interference in in vitro diagnostic tests for clotting evaluations and platelet function tests.  We use heparinase cups and vials with our TEG systems for monitoring subjects after they come off bypass.  Hepzyme from Siemens is a lyophilized version of heparinase I which is used to neutralize heparin from blood specimens for coagulation testing.  The I-Stat PT/INR version uses heparinase when monitoring subjects on oral anticoagulation therapy.  There are a lot of old references on this issue:

• Silver PJ. Neutralase (Heparinase I) as a potential heparin reversal agent in coronary artery bypass surgery. In Management of Bleeding in Cardiovascular Surgery, edited by R. Pifarré, MD, (2000) Hanley & Belfus, Inc., Philadelphia, PA.
• Ammar T, Fisher CF. The effects of heparinase I and protamine on platelet reactivity. Anesthesiology 1997;86: 1382–1386.
• Michelsen LG, Kikura M, Levy JH, et al. Heparinase I (Neutralase) reversal of systemic anticoagulation. Anesthesiology 1996-85: 339–346.
• Silver PJ, Broughton R, Bouthillier J,  et al. Neutralase reverses the anti-coagulant but not the anti-thrombotic activity of heparin in a rabbit model of venous thrombosis.   Thromb Res 1998;91: 143–150.
• Jessen LR, Wiinberg B, Jensen AL et al. In vitro heparinization of canine whole blood with low molecular weight heparin (dalteparin) significantly and dose-dependently prolongs heparinase-modified tissue factor-activated thromboelastography parameters and prothrombinase-induced clotting time. Veterinary Clinical Pathology 2008:37:363–72.
• Carroll RC, Craft RM, Whitaker GL, et al. Thromboelastography monitoring of resistance to enoxaparin anticoagulation in thrombophilic pregnancy patients. Thrombosis Research 2007;120:367–70.
• Senzolo M, Coppell J, Cholongitas E, et al. The effects of glycosaminoglycans on coagulation: a thromboelastographic study. Blood Coag Fibrinolys 2007 18:227–36.
• Mittermayr M, Margreiter J, Velik-Salchner C, et al. Effects of protamine and heparin can be detected and easily differentiated by modified thrombelastography (Rotem): an in vitro study. Br J Anaesthesia 2005;.95:310–6.
• Heres EK, Horrow JC, Gravlee GP, et al. A dose-determining trial of heparinase-I (Neutralase) for heparin neutralization in coronary artery surgery.  Anesthesia Analgesia 2001;93:1446–52.

Hepzyme’s a lot better than protamine sulfate because it doesn’t have a reversal effect when you go over the high dose and cause an anticoagulation issue like the PS does.  PS neutralizes heparin up to a point then it becomes an anticoagulant.  This is about all I have on the subject.
Regards,
Dave McGlasson
59th Clinical Research Division
Wilford Hall Medical Center
Lackland AFB, TX 78236-9908