A message from Kim Kinney at Clarian:
Hi George, I am giving a case study presentation and one of the studies is about a woman who had a homozygous high molecular weight kininogen (HMWK, Fitzgerald factor) deficiency. While we were working her up we read in a reference about the Fletcher factor (prekallikrein, PK) screening test where you incubate patient plasma with PTT reagent that contains either kaolin or silica as the activator. If after a 10-minute vs the usual 3- or 5-minute activation the time corrects, it could be a PK deficiency. Do you know why this happens?
Also, I read that moderately low PK levels are found in most homozygous HK deficient patients. Do you know why that is other then they bind together? Thanks, Kim
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Here is a summary of our February Quick Question, “How do you examine coagulation specimens for clots?”
a. We run an applicator stick through each specimen before centrifuging: 10 (17%)
b. We run an applicator stick through specimens from certain units in our medical center: 2 (3%)
c. We examine the specimen visually before and after centrifuging: 14 (24%)
d. We place the centrifuged specimen on our instrument and respond to implausible results: 33 (56%)
This QQ generated seven comments. Some are concerned that using applicator sticks before spinning activates platelets and the coagulation system. Others doubted the effectiveness of visual inspection, particularly as many institutions place at least two labels on the tube, blocking any view of the specimen. Still others indicated their concern that we report plausible results from partially clotted specimens, thereby missing potential pathological results. Bill Chamlee of the Cleveland VA suggests checking for clots after the specimen has been centrifuged and assayed, then canceling results of those that are clotted. While laborious, this may be the most effective approach. It seems this would be a fertile issue for a clinical researcher.
This arrived Wednesday from Mr. Peter Clement, MLS Student at Brigham Young University in Provo, Utah:
I am currently studying to become a Medical Laboratory Scientist. My professor is Dr. Shauna Anderson at BYU. I asked today if she had ever visited a website called Fritsma Factor, to which she replied yes and she added that she knows you. I have one question but before I just wanted to say that I have enjoyed using your site through three grueling weeks of coag that I’m almost done experiencing this Friday.
My question for you is whether or not there is a way to distinguish between high molecular weight kininogen (HMWK, Fitzgerald) factor and factor XII deficiencies without using assays? Apparently, according to old school methods you could differentiate prekallikrein (PK, Fletcher) deficiency by incubating for a longer period with kaolin and you can differentiate factor XI deficiency because it’s associated with bleeding tendency. However, all my research indicates that assays and perhaps family history are the only ways to differentiate HMWK from XII deficiency. Also, have they found anything that indicates why people with factor XII deficiency do not experience bleeding tendency?
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Here is a question I received early in January from Elpidio Pena. I apologize to Elpidio for letting this one slip through the cracks.
George: our lab performs the ristocetin cofactor (VWF activity) assay using the traditional platelet aggregation method. We are planning to change instruments and one of the instruments we are considering performs the assay by ELISA (coated beads). Any advantages/disadvantages on the ELISA method? Any particular issue to consider with this method?
Thanks.
Elpidio Pena
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Good evening Mr. George,
My name is Lydie Edwige. I’m a post graduate student in China Pharmaceutical University (Nanjing), majoring in clinical pharmacy. I’m doing my internship in Gulou Hospital (Nanjing Drum Tower Hospital). I would like to do some research about the coagulation factor X using the measurement of FXa activity. I read your article about the chromogenic factor X assay and I would like to ask you where can I possibly be able to buy the machine I need to perform my experiment? I was wondering also whether you can help me by sending me a catalogue of the appropriate machine, and the price of the machine.
Thank you,
Lydie Edwige, China Pharmaceutical University,
Nanjing-Jiangsu-China
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Happy 2010. Though 2008 and 2009 brought us a weakened economy, the opportunities in health care, and especially the medical laboratory science profession are expanding. I’ve attached a copy of the American Society for Clinical Pathology’s 2009 Laboratory Medicine wage-and-vacancy-survey-3-09, published in March, 2009. The data in this article remain accurate, and indeed, from the number of ads and anecdotes I hear, opportunities continue to expand. You may wish to download and provide this document to anyone you know who is considering a health care profession. Geo.
From: Peracha,
Mr. Fritsma: We do not have facilities for factor assays at our laboratory. I need to prepare aged plasma for correction studies. Should aged plasma have a prothrombin time exceeding 90 seconds or should it be not more than 90 seconds?
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A question from Lucas Tarquino at the University of Medicine and Dentistry of New Jersey:
Hello,
I am a medical student studying for USMLE step 2 and have a question about factor VIII deficiency. Since factors IX and X are in both the intrinsic (partial thromboplastin time, PTT) and extrinsic (prothrombin time, PT) pathways, why does deficiency of factor VIII, which is a cofactor in the conversion of factor IX to IXa and therefore also affects factor X, only prolong the PTT but not PT? I would appreciate your help in understanding this. Thank you, Lucas Tarquino.
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Coagulation Factor Assays, Uncategorized | GeorgeFritsma | 
April 7, 2010 5:18 am | 
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