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Mixing Study Dilution

From Mahnaz Sairi, Hello, George. We use pooled normal control plasma (PNP) from George King and lately found out that mixing buffer with PNP and using that as a control is confusing our physicians. Because they are asking why the control results are increasing? I really do not know why we are diluting the plasma […]

DRVVT Divisor

Maria Cordova, Mayo Labs, asks, How would calculate your DRVVT screen divisor? Hello, Maria, and thank you. You’ve opened a provocative topic and inspired me to relive fun we had with our provocative September 25, 2015 post on this subject, “Don’t Normalize the DRVVT.” This attracted perhaps the most attention of any 2015 topic. I’ll […]

Lupus Anticoagulant

ADAMTS13 Method

From Donna Lawler, University of Wisconsin, Hi George. We are investigating the possibility of bringing an assay for ADAMTS 13 activity in house. We are looking at the two methods available (ELISA and FRET) and I am wondering what your experience is with either of these assays. I would love to hear from anyone that […]

Bleeding Disorders

Rocket AF Controversy

It appears the often-criticized Rocket AF clinical trial, the results of which the FDA used to approve rivaroxaban (Xarelto), may have been flawed by the use of the Alere INRatio2 PT/INR point of care device in its Coumadin arm, recalled by the FDA in January of 2015. Read more in Medscape.

Anticoagulant Therapy

PT % Activity

This came up in correspondence yesterday and challenged an assumption. The PT is reported in seconds and INR, of course, and it was previously reported as the PT ratio (PTR), which is defined as a ratio of the patient’s PT to the mean normal PT (MNPT). But what is the PT % activity? I have […]

Screening Assays

MELD Score and INR

The model for end-stage liver disease (MELD) score attempts to objectively assesses the severity of chronic liver disease and prioritize liver transplants. The MELD formula is: MELD = 3.78×ln[serum bilirubin (mg/dL)] + 11.2×ln[INR] + 9.57×ln[serum creatinine (mg/dL)] + 6.43; where ln = natural log. MELD score is used to assess 3-month mortality: <9 = 1.9%; […]

Screening Assays

Clinical VTE Guidance

The Anticoagulation Forum has published a special issue of the Journal of Thrombosis and Thrombolysis, Volume 41; Management of Venous Thromboembolism: Clinical Guidance from the Anticoagulation Forum. The issue, consisting of 12 articles, is free online. The Forum also offers a free noon, EST March 3 webinar, Guidance for the Prevention and Treatment of Cancer-Associated […]

Anticoagulant Therapy

Anti-Xa Result is Zero

From Jennifer Watson, Centracare Health: Hello, What are your recommendations when an anti factor Xa returns with a value of 0, even after increasing doses several times? Thank you. Hello, Jennifer, and thank you for this question. Assuming the heparin dosing has been administered correctly, you may be seeing a patient who has acquired, or […]

Anticoagulant Therapy

Lipemia Statistics

Hi George, If I want to show the effect of lipemia on coag test before and after spiking a single sample, is the % difference between the baseline and spiked results enough? How do you show whether there is a statistical or clinical difference, and what stat tool to use? Thanks, Marc. Hello, and thank […]

Specimen Management

Monitoring UFH With In Vivo Hemolysis

From Andrew Goodwin, MD, University of Vermont: Hey George, I am wondering if you have experience with in-vivo hemolysis following AnigioJet mechanical pharmacothrombectomy using TPA. We had two patients over the past week in which in-vivo hemolysis was moderate to severe. In our first patient, the hemolysis was not immediate; it appeared about 12 hours […]

Anticoagulant Therapy

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George Fritsma is a medical laboratory scientist, educator, and author. George is a member of the International Society on Thrombosis and Hemostasis, the International Society for Laboratory Hematology, and the American Society for Clinical Laboratory Science.

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