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 […]

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Coagulation Factors

Apr 29 2026

george

April 2026 QQ Results: VWF Activity

Our April 2026 Quick Question reprises our 2023 QQ that asked, How do you measure VWF activity. Our 29 respondents answered as follows: VWF:RCo: 16 (56%) VWF:GP1bR: 6 (21%) VWF:GP1bM: 5 (16%) VWF:CB: 2 (7%) RIPA: 0 Our 4-1-2026 introductory QQ post attracted this comment from Dr. Emmanual Favaloro, Sydney, NSW, Australia: Hi George, of course, […]

Bleeding Disorders

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

Platelet-inflammation Interactions

Click here for a provocative open-access article describing the now established relationship between platelets and inflammatory processes: Escaig R, Kreutz L, Kaiser R, Nicolai L. Platelet effector functions in inflammation. Res Pract Thromb Haemost. 2026;10:103412. doi: 10.1016/j.rpth.2026.103412. PMID: 42027308; PMCID: PMC13100282. Abstract A State of the Art lecture titled “Platelet effector functions in inflammation” was […]

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Platelet Function Testing

Apr 23 2026

george

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 […]

Factor Assays

Iron Deficiency and Venous Thrombosis in Polycythemia Vera

Here is the abstract of a THSNA presentation, Thursday, 3-19-2026: Iron Deficiency Can Increase the Risk of Venous Thromboembolism in Hospitalized Patients with Polycythemia Vera: A Nationwide Analysis (THSNATravel Awardee) Kavya Balusu, Purva Shah, Candrika D. Khairani, Peter Kouides Rochester General Hospital, Rochester, NY, United States Background: Thrombosis is the leading cause of morbidity and […]

Thrombophilia

How to Identify PK or HMWK Deficiency

Here is a paraphrase of a question I (Geo) received on 4-3-26: “We recently evaluated a patient with an isolated prolonged APTT that corrected on mixing study. The patient has no history of bleeding and no significant family history of bleeding disorders. FVIII, FIX, FXI, and FXII assays were within normal limits. In view of […]

Bleeding Disorders

Plasminogen Deficiency and Ligneous Conjunctivitis

Dr. Amy Shapiro, Medical Director and CEO, Innovative Hematology & Indiana Hemophilia & Thrombosis Center, provided a THSNA “rare disorders presentation, Diagnosing plasminogen deficiency–clinical and laboratory considerations. Abstract: Type 1 plasminogen deficiency (PLGD) or hypoplasminogenemia is an ultrarare disorder caused by pathogenic variants in the PLG, resulting in decreased functional and antigenic plasminogen levels. PLGD […]

Thrombophilia

Mixing Study with Shortened Incubated PTT

Here is a paraphrase of a recent question: “What accounts for a shortened post-incubation PTT compared to the immediate mix result?” Example: Patient PTT: 50 s Commercial PNP PTT: 30 s Immediate mix result PTT: 40 s 2-h Incubated result PTT: 37 s Frequent expert contributor Dave McGlasson suggests the patient’s plasma should be checked […]

Mixing Studies

April 2026 Cheat Sheet

Click here to read our April 2026 Cheat Sheet. If you would like to receive your own “push” Cheat Sheet by email, please apply using the form on the right. The emailed Cheat Sheet adds the list of March posts at the bottom.

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Cheat Sheets

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May 2026 QQ: Proconvertin

April 2026 QQ Results: VWF Activity

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

Platelet-inflammation Interactions

FXI and XII Non-parallelism Puzzle

Iron Deficiency and Venous Thrombosis in Polycythemia Vera

How to Identify PK or HMWK Deficiency

Plasminogen Deficiency and Ligneous Conjunctivitis

Mixing Study with Shortened Incubated PTT

April 2026 Cheat Sheet

George Fritsma MS MLS

Cheat Sheets from George

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