APTT normal ranges

[nziegler]

This question goes out to users of IL TOP 500 running PTT's using SynthaSil reagent:

What is your current normal range?

 

Ours is currently 21-36 seconds, but alot of our pre-admits are flagging high.  I ran 40 pre-admit and ambulatory surgery patients as part of a new lot workup, but i'm getting 24-42 seconds - which seems kinda high.  So i'm just wondering what some other places might be using before i continue my workup....

[SMILLER]

We are running some old Advances, with the IL APTT-SP reagent, but what any other lab's normal ranges are should make no difference to what you establish yours as anyway.

 

For our stuff, a few years ago, IL (Beckman-Coulter) said that there would be little variation from lot to lot in the future as far as sensitivity.  But you still have to validate both the normal range and the heparin  therapuetic range.  It sounds like you have data that shows that your normal range has shifted.  I would call IL and ask them if they have had other labs reporting shifts as well before proceeding.  Or have you switched to a totally new type of reagent? -- in which case you would almost expect a shift.

 

In any case it sounds like you may have to change you normal range for APTTs.  You also need to look at results for patients on heparin!

 

Scott

[nziegler]

Thanks Scott. I have no idea when the last true normal range study was done.  The problem is that in the past, whenever we would switch lots, we would "validate" the normal range in use.  This meant that all specimens saved already fell within our range, guaranteeing validation of the range.  (i just took over about a year ago and am trying to do things the right way)  I'm not sure when we switched from the SP to the SS reagent.

i do have message out to my technical rep to see how others are running and am waiting for feedback from other sites in my system.

 

Luckily, i don't have to worry about heparin response curves - we run the heparin assay!

[SMILLER]

A Xa assay!  That would be nice!  So no one there uses an APTT to monitor heparin therapy?  Are they all on LMW heparin?

 

Scott

[Auntie-D]

Ours run about what you quote for your original normal range. You need to set your own normal range based on the patient demographic. One thing that bugs me is you can't calibrate APTTs… Other than that TOPs are wonderful!

[nziegler]

Yes, the Xa assay is wonderful!  It's calibrated with a hybrid curve, so we can report both unfractionated and LMW.  99.9% of our testing is unfractionated for the inpatients.  No more heparin response curves!  So the only PTT's we run (for the most part) are ER, pre-surgical, and ambulator surgery.  And it shouldn't even be used for pre-surg or ASU.

[Alan Neal]

_Hi

_{We use a mixture of ACl 500 (x3), 700 LAS (x2) across 4 different locations and have recently validated the reference interval of new Lot No of Synthacil.}

_{We routinely will do min 20 normal samples each site, with collective group of 80+ pool of results (Aslo do heparin spiking each site, plus one site peform factor 8 & 9 sensitivity evaluation).}

_{We have found our reference range to be consistently 26 - 36 sec (& have not changed for the past 3 lot No's used) - very happy with Lot to Lot consistency for all aspects reviewed,}

_{We also initially did APTT V's anti-Xa assay results and information was very simular to IL information.}

 

_{Alan NZ}

Edited January 3, 2014 by Alan Neal