George received a note from a colleague who has three separate specimens from a patient with prolonged partial thromboplastin times (PTTs) that further prolong as they stand at ambient temperature over periods of several minutes, for instance, 57s, 151s after 20 minutes, and 174s after 2 hours. Mixing studies consistently correct. They’ve tested them on both electromechanical and optical instruments. No anticoagulants, the serum protein electrophoresis is normal, and the factor V level is 162%. George shared the question with several experts while attending the ASCLS/AACC annual meeting in Houston, and so far we have no answers. Any ideas?
Here is a follow-up from George’s colleague, sent August 9, 2013: “We ran several PTTs from different days and obtained highly erratic numbers. To muddy the waters more, the PTT went up on repeat on all but two, when they went down from around 70s to 40s. Also the thrombin, fibrinogen and prothrombin times (PTs) were normal. The D-dimer was just slightly elevated. We did send out for high molecular weight kininogen (HMWK) and prekallikrein (PK), they are not back yet, however I have never seen results so erratic with a deficiency of either of these. Also, the IX, XI and XII were normal.”
Here is an additional follow-up sent August 19, 2013: “The PK is < 1%!”
To our participants, do you have an explanation as to why PK deficiency would generate erratic PTT results?
We recently had a patient with variations in the aPTT throug
We recently had a patient with variations in the aPTT through out different collections and admission dates; anywhere from 64 through 99 seconds. We performed mixing studies which demonstrated marked correction to reference ranges. All factors were within normal limits. Specimen sent for PK and the results were also < 1.0%!
For several years I have been using IL Synthasil PTT reagent
For several years I have been using IL Synthasil PTT reagent and have seen this erratic PTT phenomenon twice with Prekallekrein and once with HMWK deficiency. PTTs ranged from low 60s to around 150, on the same sample. I think it must be related to other contact factor compensation and activation and how long the sample sits. I suspect the type of reagent activator will influence this too. We do not quantify our PK or HMWK, but do a mixing study for correction using PK or HMWK deficient plasma to pin point the culprit, so I really don’t know how deficient these individuals are.
It is possible to have such results, for instance, acquired
It is possible to have such results, for instance, acquired hemophilia with type 2 kinetics. What about Factor VIII, not mentioned,factor VIII inhibitor will be useful. Vilas Hiremath.