From Michele L. Drejka, Lead Technologist, Barnabas Health, Newark, NJ:
Hi George, Sorry to be redundant, but I posted this in ‘Comments,’ however I actually need an answer to my question below, so I am repeating here: Regarding prolonged activation times-I’m getting frustrated. I had more success with playing with this 15 years ago! However, this is what our lab does for prekallikrein (PK, Fletcher) and high molecular weight kininogen (HMWK, HK, Fitzgerald) deficiencies. First we do a silica-based partial thromboplastin time (PTT) mixing study with incubation. When it corrects without prolonging and all other factors are normal we go to a specific PTT mix using known PK-deficient and then HMWK-deficient plasma. When we find correction with one and non-correction (bingo!) with the other mix then we know which deficiency we have. Do you see any flaws in this rational? P.S. We do not quantify these two factors because of maintenance on assays that would be rarely used.
Hi, Michele, thanks for re-posting your question, and no, I find no flaws in your approach. Most of our participants know that the three contact factors are factor XII (Hageman), PK, and HMWK, and that deficiencies of any of these three are not associated with bleeding disorders. In the latest edition of Kitchens CS, Kessler CM, and Konkle BA. Consultative Hemostasis and Thrombosis. Elsevier, 2013 (just out), Escobar MA and Roberts HR, in chapter 5 give the incidence of congenital deficiency as factor XII and PK as unknown, and HMWK as very rare (less than 1 in 1,000,000). In my experience, factor XII deficiency is relatively common, though one only occasionally encounters PK, and especially HMWK deficiencies. In fact, I note that neither Precision BioLogic Inc nor George King Bio-medical, Inc. offer a HMWK-deficient plasma, so I’m curious about your source.
There is a “poor-man’s” approach to PK identification, detailed (by Cindy Johns) in the 1982 textbook Laboratory Evaluation of Coagulation, by the late Dr. Douglas Triplett. When a PTT using silica, Celite, or kaolin, but not ellagic acid activator is prolonged, incubate the reagent and plasma mixture for 10 minutes instead of 3 and repeat. If the PTT is corrected to within the reference interval, the deficiency is PK. Triplett wrote that PK deficiency is seen in newborns, and acquired PK deficiency is seen in liver disease, and references Hattersley PG, Hayse D: The effect of increased contact activation time on the APTT. Am J Clin Pathol 1976;66:479.
two more (later) references for increased APTT incubation as
two more (later) references for increased APTT incubation as a diagnostic approach to detect PK deficiency:
Asmis LM, Sulzer I, Furlan M, Lämmle B. Prekallikrein deficiency: the characteristic normalization of the severely prolonged aPTT following increased preincubation time is due to autoactivation of factor XII. Thromb Res. 2002 Mar 15;105(6):463-70.
Corno AR, et al. Automated APTT cycle for the rapid identification of plasma prekallikrein deficiency. Thromb Res. 2010 Aug;126(2):e152-3.
We have a patient we think has a PK or HM
We have a patient we think has a PK or HMWK deficiency. (The levels were sent out yesterday.) We are seeing some interesting results here. It started with a 107 sec PTT which completely corrected in the 1:1 mix. The interesting part is that after a 2-hr incubation in the waterbath, the straight PTT went down to 60! Today, I did the crude method with a 3 and 10 minute incubation in a manual PTT with silica activator. The 3 minute incubation had a PTT of 141, which then went to 41 sec after a 10 min incubation. So we really think this will turn out to be a PK/HWMK deficiency, but are confused by the shortening of straight patient in the mixing study. Any ideas?
Hello, Heather, good to hear from you, and this is the typical response you find in a prekallikrein deficiency. `i don’t know why this happens, but it is referenced in the 1984 Triplett textbook and is used as a quick method for identifying PK deficiency. I will be interested to learn what results you get from your reference laboratory.
Thanks for the update. I think that George King Biomedical’s
Thanks for the update. I think that George King Biomedical’s HMWK-deficient donor is now unavailable, so your plasma is worth its weight in gold, as is your current patient’s plasma. That patient may want to get in touch with the people at George King! Also, to Joyce, I really don’t know why the ellagic acid PTT reagent doesn’t work, perhaps a chemist is lurking on the site and can answer. Geo.
My HMWK deficient plasma is old from George King Biomedical,
My HMWK deficient plasma is old from George King Biomedical, and has been ‘expired’ for years but it has been kept at -80C the entire time. Meanwhile our lab did have one HMWK deficient patient (2009) whose plasma we verified by the specific mix, and have saved that plasma. I checked the Aniara website a few months ago where they had immuno-depleted HMWK plasma, but now I don’t see it in the search anymore. I don’t know if they still offer it. Thanks for your help.
I am interested in why when using an APTT with
I am interested in why when using an APTT with ellagic acid, the increased incubation does not work for PK deficiency. We have used the increased incubation method for investigating prolonged APTTs that could not be explained by the usual reasons for many years (orobably since 1982). It seemed to pick up more deficiencies when we used kaolin as the activator, not so many when using silica and none with ellagic acid (since 2007) as activator