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Case Study: Prolonged PTT

Hi George, I have a 33 yo HIV positive non-compliant female patient with chronic kidney disease. Labs: PT: 13.4 (11.7-14.2) PTT: 47 (23-33) FIB: 300mg/dL D-DIMER: 1.61 FEU Where do I go from here? Richard Larsen, US Army Hi, Richard, I suggest your next step is a mixing study for the prolonged PTT. This will […]

Anti-Xa Validation Request

If you can assist Dr. Pena, please respond via the “comments” section below. This was sent through Dr. Marisa Marques, University of Alabama at Birmingham Hospital: Dear Marisa, how are you? I work for Norton Healthcare in Louisville, KY. We are trying to set up our assay for anti-Xa for low molecular weight heparin. We […]

Applicator Sticks: How to Detect Clots

From Bill Chamlee at the Cleveland VA: Hi George, I stumbled onto your site while researching the new lower potency heparin/therapeutic range issue. I was interested in your quick question about checking for clots. I don’t do any of the four choices you list. I use two applicator sticks to check for clots after centrifuging […]

Switching to Fondaparinux

I’m a registrar in an ICU at Menofyia University, Menofyia, Egypt. We have been thinking about using the new drug, Fondaparinux. Could you please give me more details about the drug, when to monitor its efficacy (all patients or high risk only?) and how do you use the anti-factor Xa assay; i. e. the kits […]

Heparin Anti-Xa

From Dr. David Floering: Is anyone routinely using heparin anti-Xa assay to monitor heparin instead of PTT? If so, what are the experiences? David Floering, MD Medical Director, Pathology Atrium Medical Center Middletown, Ohio Dr. Floering, thank you for your question. I have several acquaintances who have successfully converted from PTT to the chromogenic anti-Xa […]

Bethesda Titer Formula

Two messages from Beaumont on Bethesda titer calculation: Hi George, I wanted to ask you if you know the formula to calculate the amount of factor inhibitor BU for the classical Bethesda assay. We have been graphing the results on the log log paper. We are working on a new LIS system and would like […]

Collagen Lag Phase Software?

Dear George, We are in the process of getting new software for the lab. I would like to know if there is a formula available for calculating the collagen lag phase (T 1/2) . Our older Chronolog aggregometer does not have this feature. Currently our techs are manually drawing, measuring and calculating it. Thank you, […]

D-dimer and Aging

Once again, Kim Kinney (Clarian, Indianapolis) drives me to the books. Hi George, Every article I have ever read talks about age and increased dimer levels but I never have seen a reason. Why do dimers increase with age? Acute phase proteins? Kim, yes, I suggest that D-dimer is a marker of inflammation, and not […]

More on Shortened PTTs

Here is a reference Dr. Larry Smith found describing the relationship of a short PTT with other coagulation parameters followed by three references found by Dr. Elaine Keohane on the same topic. Blood Coagul Fibrinolysis. 2010 Mar;21(2):152-7. A laboratory evaluation into the short activated partial thromboplastin time. Mina A, Favaloro EJ, Mohammed S, Koutts J. Department of Endocrinology, Institute […]

More on Checking for Clots

Hi George. At Clarian, we still check every coag tube for a clot before running it on our analyzers. With our ever-increasing work load, I am debating whether or not to let this old habit of mine go. I have had techs run samples that are clotted to see what range of results I get […]

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George Fritsma is a medical laboratory scientist, educator, and author. George holds faculty appointments with Rutgers University and Michigan State University, and is a member of the International Society on Thrombosis and Hemostasis, American Association of Clinical Chemists, and American Society for Clinical Laboratory Science.

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