Factor Assays

Factor VIIa-AT Assay

Paul Riley, PhD, mentions Stago’s new research use only assay Asserachrom VIIa-ATthat measures the activated factor VIIa-antithrombin complex (VIIa-AT, similar to the familiar thrombin-antithrombin complex), an analyte elevated in hypercoagulable states. Dr. Riley suggests the assay may be a potential surrogate biomarker for activated coagulation states. The press release and a series of references are attached […]

Silica-based PTT Reagent for Factor VIII

From Carol Gizzi at Baycare in Florida, We perform the factor VIII assay with a silica activated APTT ( PTT) reagent. We monitor hemophilic patients. Recently we were asked to switch our reagent to a PTT reagent using ellagic acid as the activator. We do not understand the reason for the request. We thought the silica activated […]

Validate the Fibrinogen Assay

Because in Romania we don’t have books, guidance or procedures about validation I want to know if for the fibrinogen validation it is necessary to establish the lower limit of detection (LLD) and if the manufacturer does not provide information about the CV% for precision and accuracy what can I do? Best regards, Monica Truta, Clinical […]

Case: INR 2.2 but VII and IX are Normal

Here is a puzzler from Pam Owens at Tricore Reference Laboratories in Albuquerque. Hi George, we recently encountered a patient on warfarin (confirmed by clinician) whose international normalized ratio (INR) is 2.22, protein C and S are in the 30–40% range, but her factors VII and IX are “slam” normal. Have you ever encountered this? What could cause it? […]

Anticoagulant Therapy

Monitoring Factors after Plasma Administration

From “japgi.” Hi! I’d like to get some information (if possible a reference) on this clinical situation. If a patient with an uncharacterized bleeding disorder has been transfused plasma or cryoprecipitate in an emergency setting, how soon afterwards can one do a coagulation screen to avoid the results from getting compromised by the transfused factors? […]

Bleeding Disorders

Bethesda Titer Protocol

Hello George! Our laboratory would like to start offering the factor inhibitor assay (Bethesda titer). We currently do special coagulation tests for several hospitals and clinics. I was wondering if there is a procedure you are willing to share. Sincerely, Maria E. Martinez, BS MT (ASCP), Senior Medical Technologist–Coagulation, Orlando Regional Medical Center. Hello, Maria, and […]

Bleeding Disorders

Low Factor VIII Reporting

Hi, Using the ACL 9000, we have seen some low results for the factor VIII activity test, as low as 0.3%. In those instances we were told to dilute the sample 1:2, and retest. On those retests we get the same results, should we report the result as it is or with a less than […]

What is Thrombokinase?

Does anyone remember using the term “thrombokinase?” Kathryn Doig, PhD, Dean of the Michigan State University College of Natural Sciences, and Professor ofBiomedical Laboratory Diagnostics writes: Hi George. We have a grad student who is doing a project related to hemostasis. Along the way, she used the term “thrombokinase” which I had not heard in quite some time. […]

Fibrinogen Assay Reportable Range

Dear George, I am using an STA Compact from Diagnostica Stago. I would like you to throw some light on validating the reportable range of the fibrinogen assay which is 60–1200 mg/dl. How can I obtain plasma with such high levels of fibrinogen? Regards, Dr. Shabnam Roohi. Hello, Dr. Roohi. For assistance I went to Dr. Ali […]

Mixing Study Result: Long PT & PTT

From “Begumra:” Deficient factor in case of prolonged PT and PTT result that corrected with the addition of normal pooled plasma. All other screening tests are normal. I think it is factor V. Can you suggest that it is right? Hello, and thank you for your question. Assuming the patient is not on heparin or […]

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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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