Unexpectedly Prolonged PT

Unexpectedly Prolonged PT
Apr 15, 2011 5:52pm

Hi, I’m from Argentina and I work in a hemostasis lab. I have a little question for now: an anticoagulated woman had a prolonged prothrombin time (PT ). The coagulometer read +++, meaning more than 300 seconds and an INR more than 20. However she wasn’t bleeding. What could be the reason?

Hello, and thank you for your question. Assuming your coagulometer is working properly and the reagents are valid, the most likely possibility is that the specimen was partially clotted and the coagulation system proteins had been consumed. This occurs, for instance, when the specimen is not properly mixed immediately after collection, and the clot may go undetected after centrifugation. Additionally, but less likely, the specimen may have been stored for too long or at too high a temperature, causing the deterioration of some of the coagulation factors. I suspect if you repeat the assay on a properly collected specimen, the results will be in the respected range. Geo.

2 Comments

Hi, I’m from Argentina and I work in a hemostasis lab. I have a little question for now: an anticoagulated woman had a prolonged prothrombin time (PT ). The coagulometer read +++, meaning more than 300 seconds and an INR more than 20. However she wasn’t bleeding. What could be the reason?

Hello, and thank you for your question. Assuming your coagulometer is working properly and the reagents are valid, the most likely possibility is that the specimen was partially clotted and the coagulation system proteins had been consumed. This occurs, for instance, when the specimen is not properly mixed immediately after collection, and the clot may go undetected after centrifugation. Additionally, but less likely, the specimen may have been stored for too long or at too high a temperature, causing the deterioration of some of the coagulation factors. I suspect if you repeat the assay on a properly collected specimen, the results will be in the respected range. Geo.

By Biochemist Domingo Moreno
Apr 16, 2011 9:37pm
Thank you. I forgot to tell that the patient told me she takes 4 mg Acenocumerol per day. I took the sample and centrifuged immediately. Sorily, the patient didn't return to control. Next time I will try to take new specimen.

From George: thank you for the follow-up, from your description it seems the specimen was managed correctly, however this still appears to be an analytical error, as there is no information that leads towards a patient concern. I will be interested to learn about the next specimen.
By Biochemist Domingo Moreno
Apr 20, 2011 8:58pm
Thank you. I will pay more attention to other similar case, and I'll take a second specimen to confirm the INR.

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