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

Read more »

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 are having a hard time finding another laboratory to do the initial correlation. We use a BCX instrument. We use a straight curve for the anti-Xa for unfractionated
heparin and use exogenous antithrombin in the test system. My questions are:

1.  Do you know of any lab that uses a similar system?
2.  Is there an alternative for the correlation, if we do not find another
(reference) lab?

The best for you and your lovely family. Elpidio

Elpidio Pena, MD
Medical Director Transfusion Services
Norton Healthcare

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 and running first.  The sticks can act as an activator and my experience is that the PTT is usually shorter after rimming for clots, more noticeably of course in abnormal and therapeutic specimens.  And I still don’t understand how you can identify a clotted specimen by looking at the test results.  Sure, sometimes the low PTT is a dead giveaway.  But not always–the normal looking PTT could really be high.  And what if it’s only a PT-INR?  I know CAP lists that as an acceptable choice, but I don’t know why. With my method, I have seen plenty of clotted specimens with perfectly “plausible” results.  But are they accurate results?  I reject them.  So does CAP imply clotted specimens are OK if they give plausible results?
Read more »

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 and the frequency of monitoring? is it a daily blood sample in the case of the prophylactic dose (2.5 mg)? Where could I find these kits? could you give me the address of any specialized company in coagulation monitoring. Hagar

Read more »

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

Read more »

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 to program a formula to calculate the result.  I would appreciate any help you could give us.

Karri Henderson MT(ASCP)
Beaumont Laboratory
Coagulation, Assistant Supervisor
Clinical Pathology, Royal Oak

and:

We at William Beaumont Hospital, are installing new software for the lab.  Is there a formula for calculating the Bethesda inhibitor titer?  Currently our techs graph the results by hand. Thank you,

Diane Farrah, BA, BS, MT
William Beaumont Hospital
Royal Oak, Michigan

(See Laura Taylor’s comment added 2/26/2010)

Read more »