August 2026 QQ Summary: Coagulation Control Proteins

Our August 2026 QQ asked: “Which is NOT an endogenous coag control protein?” Our 29 participants answered… 1. Antithrombin: 1 (3%) 2. APC: 2 (7%) 3. TFPI: 4 (14%) 4. VKA: 22 (76%) VKA is the correct answer. VKA is the general term for the therapeutic anticoagulant warfarin (once called Coumadin®), which suppresses vitamin K […]

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Bleeding Disorders

Jul 28 2026

george

August 2025 QQ: Coagulation Control Proteins

Our August 2026 Quick Question is a simple quiz that asks, “Which is NOT an endogenous coag control protein?” This is your opportunity to review the plasma-based coagulation mechanism and recall the functions of the control proteins, available in our Educational Module entitled Coagulation Overview. One of these is NOT an endogenous control protein for […]

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Quick Question Archive

May 29 2026

george

May 2026 QQ: “Proconvertin” Response

Our May 2026 Quick Question was a quiz and a “walk down memory lane.” Our 28 responders to the lead, “What factor was once named Proconvertin or SPCA?” responded as follows: IV: 2 (7%) V: 4 (14%) VI: 1 (4%) VII: 18 (64%) IX: 3 (11%) We’ve largely abandoned our proper noun terminology except for […]

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Quick Question Archive

May 23 2026

george

Cell-based Coagulation Model

Our Coagulation Overview Module, linked on May 15, 2026, may be more accurately called the Plasma-based Coagulation Overview Module. The plasma-based coagulation “cascade” model, described in Davie EW, Fujikawa K, Kisiel W. The coagulation cascade: initiation, maintenance, and regulation. Biochemistry. 1991;30:10363–70. doi: 10.1021/bi00107a001. PMID: 1931959, is the basis for clot-based tests, the PT, PTT, TT, […]

Coagulation Factors

Tissue Factor Activity and Ischemia

Access this open-access article that describes a relationship between plasma TF levels, cancer-related ischemia, and elevated D-dimer: Gon Y, Kawano T, Kitano T, et al. Tissue factor activity and 1-year mortality in patients with active cancer and acute ischemic stroke: findings from the SCAN study. Res Pract Thromb Haemost. 2026;10(1):103347. doi: 10.1016/j.rpth.2026.103347. PMID: 41695667; PMCID: […]

Arterial Thrombosis

Cord Blood VWF & FVIII Levels

On Monday, 5-18-26, Stuart Lind, MD, University of Colorado Hospital and School of Medicine, asked, “Would you know of any primary references that validate cord blood levels?” A PubMed search yielded this reference describing VWF levels, available from your medical library: Schneider DM, von Tempelhoff GF, Herrle B, Heilmann L. Maternal and cord blood hemostasis […]

Coagulation Factors

Coagulation Overview Module

We’re reviewing our Educational Modules for timeliness. Many institutions use Coagulation Overview for both introductory education and advanced review. You can complete it in <30 minutes, but you may wish to stop at intervals to observe the various diagrams in detail just by pressing the space bar. The module supplements Walenga JM, Krom KN: Chapter […]

Coagulation Factors

May 2026 QQ: Proconvertin

Our May 2026 QQ is another “memory lane” quiz that asks, “What factor was once named proconvertin, stable factor, autoprothrombin I, or serum prothrombin conversion accelerator (SPCA)? For space purposes, the stem is shortened to ‘Proconvertin or SPCA?‘ ” Click first on Posts to navigate to the QQ in the right column. Corriveau DM, Plasma […]

Coagulation Factors

A Comparison of The Clauss Fibrinogen Assay with the Prothrombin Time-derived Assay

Click here for an open-access 2026 article comparing the time-honored Clauss fibrinogen assay with the PT-derived assay: Latona A, Hill K, Rane M, Ho A, Mitra B. Diagnostic accuracy of Clauss and prothrombin time-derived fibrinogen against rotational thromboelastometry FIBTEM-A5. Res Pract Thromb Haemost. 20266;10:103439. doi: 10.1016/j.rpth.2026.103439. PMID: 42027315; PMCID: PMC13100266. Abstract Background: Fibrinogen levels may […]

Factor Assays

FXI and XII Non-parallelism Puzzle

Sacha Uljon, MD, PhD, Medical Director, Core Laboratory, Massachusetts General Hospital, sends us an FXI and FXII puzzle: This is a question for Werfen ACL Top users: We have noticed non-parallelism for FXI and FXII, increasing factor levels with increasing dilutions, even in patients without LAC. We’ve done a lot of troubleshooting; this seems to […]

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Factor Assays

Coagulation Factors

August 2026 QQ Summary: Coagulation Control Proteins

August 2025 QQ: Coagulation Control Proteins

May 2026 QQ: “Proconvertin” Response

Cell-based Coagulation Model

Tissue Factor Activity and Ischemia

Cord Blood VWF & FVIII Levels

Coagulation Overview Module

May 2026 QQ: Proconvertin

A Comparison of The Clauss Fibrinogen Assay with the Prothrombin Time-derived Assay

FXI and XII Non-parallelism Puzzle

George Fritsma MS MLS

Cheat Sheets from George

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