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 […]

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Mixing Studies

Feb 6 2026

george

Review: Hemostasis Biomarkers

Here is a January 2026 comprehensive review of commonly used and esoteric hemostasis disorder biomarkers in downloadable format: Reardon B, Pasalic L, Favaloro EJ. Biomarkers of coagulation disorders—where to from here? Biomolecules 2026: 16, 235. https://doi.org/10.3390/biom16020235. Abstract Disorders of thrombosis and bleeding contribute to a significant morbidity and mortality burden worldwide. Correctly identifying contributing factors […]

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Global Hemostasis Assays

Feb 4 2026

george

Review: Clot Waveform Analysis

Click this open-access article that reviews attempts at harmonization of clot waveform analysis: Tan JY, De Guzman MRT, Wong WH, et al. Decoding clot waveform analysis: toward better understanding and harmonization. Semin Thromb Hemost. 2026. doi: 10.1055/a-2778-9810. PMID: 41506647. Abstract Clot waveform analysis (CWA) extends routine coagulation assays (activated partial thromboplastin time [PTT] and prothrombin […]

Screening Assays

Meta-analysis: D-dimer Safely Excludes Pulmonary Embolism in Cancer

Obtain this provocative article from your medical library: Vrotniakaite-Bajerciene K, Mallick R, Takada T, et al. Safety and efficiency of D-dimer testing in combination with clinical decision rules to exclude pulmonary embolism in patients with cancer: individual patient data meta-analysis. J Thromb Haemost. 2025:S1538-7836(25)00839-6. doi: 10.1016/j.jtha.2025.10.035. PMID: 41354153. Abstract Background: Failure rates of clinical decision […]

Thrombophilia

PT and PTT Illustrated Mechanisms

For an illustrated overview of the hemostasis mechanisms associated with the PT and PTT, obtain this article from your medical library: Harris NS, Marin MJ, Butenas S. Beyond prothrombin time and activated partial thromboplastin time: coagulation in vivo-an illustrated review. Lab Med. 2025;56:438–47. doi: 10.1093/labmed/lmae125. PMID: 40319459. Abstract The steps that initiate coagulation in vivo […]

Coagulation Factors

Manual Tilt Tube PT

Here is an open-access editorial commenting on the tilt-tube PT requirement for establishing the reagent thromboplastin ISI. Favaloro EJ. Manual tilt tube method for prothrombin time: a commentary on contemporary relevance. Clin Chem Lab Med. 2025;63:1239–42. doi: 10.1515/cclm-2025-0157. PMID: 39985393.

Screening Assays

Impact of Sodium Citrate Levels on Coagulation Assays

Click here to see a poster describing the effects of varying citrate concentrations on clot-based assays: Rahman M, Bruhm M, Black KM, Sadeghi-Khomami A. Impact of sodium citrate levels in coagulation assays: A controlled ex-vivo study. Poster Presented at ISLH 2025. The findings will help us determine the effects of underfilling or overfilling blue-closure tubes […]

Specimen Management

September 2024 Quick Question Response: PTT and FVIII Level

Our September 2024 Quick Question drew 59 responses and asked: “At what FVIII activity level should the PTT become prolonged?” Our answers were: 60 U/dL: 6 (10%) 40 U/dL: 37 (63%) 10 U/dL: 12 (20%) 1 U/dL: 4 (7%) Most of us chose the correct answer. The PTT “partial thromboplastin” manufacturers develop their reagent to […]

Bleeding Disorders

September 2024 Quick Question: PTT

I (Geo) prefer PTT to APTT or aPTT because the “A” or “a” is superfluous. Laboratory scientists no longer offer an “unactivated” PTT. The “partial thromboplastin” reagent consists of a phospholipid or combination of phospholipids that may include animal, plant, or synthetic sourced phosphatidylserine, phosphatidylcholine, phosphatidylinositol, sphingomyelin, and/or phosphatidylethanolamine. Accompanying the phospholipid is one of […]

Blog

Lot Conversion for CaCl2?

From Cynthia Hollis on 2-2-24: I had someone ask me why I didn’t do a lot conversion for changing lots of CaCl2 that I use in my APTT assays. I was unable to give them a satisfactory answer. Can you explain it for me, please? From Geo: Hi, Cynthia, thanks for your question. I checked […]

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Screening Assays

Screening Assays

Mixing Study with Shortened Incubated PTT

Review: Hemostasis Biomarkers

Review: Clot Waveform Analysis

Meta-analysis: D-dimer Safely Excludes Pulmonary Embolism in Cancer

PT and PTT Illustrated Mechanisms

Manual Tilt Tube PT

Impact of Sodium Citrate Levels on Coagulation Assays

September 2024 Quick Question Response: PTT and FVIII Level

September 2024 Quick Question: PTT

Lot Conversion for CaCl2?

George Fritsma MS MLS

Cheat Sheets from George

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Quick Question