Case Study: Prolonged PTT

Case Study: Prolonged PTT
Mar 9, 2010 6:22am

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

Hi, Richard, I suggest your next step is a mixing study for the prolonged PTT. This will help you determine if the patient has a factor deficiency secondary to the kidney disorder or an inhibitor, possibly a lupus anticoagulant. May also want to determine if she has bleeding symptoms, as this will weigh into the diagnosis. Please send the reference interval for your D-dimer also. Thanks. Geo

5 Comments

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

Hi, Richard, I suggest your next step is a mixing study for the prolonged PTT. This will help you determine if the patient has a factor deficiency secondary to the kidney disorder or an inhibitor, possibly a lupus anticoagulant. May also want to determine if she has bleeding symptoms, as this will weigh into the diagnosis. Please send the reference interval for your D-dimer also. Thanks. Geo

By Rlarsen
Mar 9, 2010 9:04am
George, perhaps much of my original post got lost.
Ref interval for d-dimer= 0.5
Thrombin time was prolonged @27 sec (15-20)
Reptilase time was prolonged @38 sec (20-25)
1:1 PTT did correct to 33 sec
1:1 TT and reptilase times did not correct (24 and 35 respectively)
DRVVT was normal @38 sec (30-40)
Why did mixing studies correct the PTT but not the TT
or reptilase times? PTT post hepzyme was 45 sec. Thanks
Richard
By George Fritsma
Mar 10, 2010 7:54am
OK, this helps, Richard. I'm not sure about the reptilase time result, but I wonder if the thrombin time is caused by an anti-bovine thrombin inhibitor. Has the patient had a previous procedure in which the surgeon used fibrin glue?
By George Fritsma
Mar 11, 2010 5:00am
Richard, one more possibility is hinted at by the elevated D-dimers. It may be that fibrin degradation products are interfering with the reptilase and thrombin time results. It would be interesting to track the D-dimer results with the TT and RT over a few days to see if both resolve.
By Coag Research Dave McGlasson
Mar 11, 2010 8:03am
Richard, I agree with Mr. Fritsma. The reptilase time is an assay that differntiates between heparin contamination and abnormalities of fibrinogen(s)and its breakdown by products. An elevated thrombin time and a normal reptilase time is indicative of heparin contamination. The reptilase is normal in the presence of heparin due to the fact that the assay is not influcenced by anti-thrombin. If both assays are elevated this may be indicative of an elevation of fibrin degradation products of some kind. An excellent article on this subject is by Van Cott EM, Smith EY, Galanakis DK (August 2002). "Elevated fibrinogen in an acute phase reaction prolongs the reptilase time but typically not the thrombin time". Am. J. Clin. Pathol. 118 (2): 263–8. Hope this helps.

Dave McGlasson
By Rlarsen
Mar 11, 2010 9:41am
Thanks. This was a request for mixing studies due to a prolonged PTT. As part of any investigation of a prolonged PTT we perform a Thrombin Time to r/o heparin contamination. When the TT is prolonged I do additional testing to determine the cause (hypofibrinogenemia, dysfibrinogenemia, elevated FDPs, Heparin or Direct Thrombin Inhibitors). I did not expect such a minimally elevated D-dimer value to have this effect but agree with you it is the most likely cause. A nice little study is determine at what level of D-dimer the TT becomes prolonged. Thanks again.
Richard

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