Talk:Prothrombin time

what does this sentence mean?
"For the prothrombin time test the appropriate sample is the blue top tube, or sodium citrate tube, which is a liquid anticoagulant." Something is missing from this sentence, and does this have to be so specific as to the tube type? --74.179.99.253 (talk) 02:09, 10 December 2009 (UTC) and so Yes, it has to be that specific. The tube is a 3.2% sodium citrate blood collection tube. In early years it could also be a 3.8% citrate tube, but these tubes have largely been abandoned, and the sensitivities of thromboplastins at the international level have all been done with 3.2% citrate.

reference method
the reference method defining the test is a manually eyeballing test performed by mixing plasma from the sample with reagent and then look for the clot by looking for wrinkles on the samples surface when tilting the reaction vial and then record the time. All kept in a warm 37 degree bath.

the samples used for defining the reference sample comes from frosen down samples from the WHO.

No, the samples are not from the WHO. The procedure is a WHO guideline. The normal and coumdadin plasma samples are obtained locally.

81.170.221.51 21:55, 6 January 2007 (UTC)

external laboratory quality organisations
EQUALIS and SKUP and NOKLUS are some organisations that monitors labs externally by sending out samples to the laboratories and collecting results in order to see if the labs are genereating results comparable to each others.

optical vs. mechanical
"takes to clot is measured optically," Clots are also measured mechanically, even in this day in age. Most hospitals use (as a backup to optical systems) mechanical impedance methods in situations of extreme hemolysis/lipemia, when most wavelengths which measure clot formation would be affected by such interferences.

Just saying, and I didn't want to muck up such a great article by changing without discussing it first.

oops
OOPS!!, i think i got mixed up, extrinsic/intrinsic. Hahaha, serves me right for looking at internet references!, i'll just move some of it to APTT if need be. T 05:41, 11 Apr 2004 (UTC)

False alarm, it was just a one-off typo. Fixed. T 05:48, 11 Apr 2004 (UTC)

NPT
NPT "Near Patient Testing" is called POC "Point Of Care" in the dia-buisniess termnology.

I added a bit on NPT, as I felt this needed covering too. If I get round to it I might put a photo or two in. Please feel free to fiddle with this - I am an ex-wikipedian doing cold turkey and trying largely successfuly to stay away, so I won't be looking in here all that often, I hope! 82.35.17.203 18:25, 15 Nov 2004 (UTC)


 * Nice one. If you're an ex-Wikipedian, couldn't you have inserted a few more links? :-) JFW | T@lk  22:29, 15 Nov 2004 (UTC)


 * heheh thank you. Unfortunately my status as an ex-wikipedian means I can give myself some confused moral letout which means I don't have to ... don't ask me to explain this, it'll never stand up in court. :) 82.35.17.203 20:25, 17 Nov 2004 (UTC)

Hi I am not sure how to add this citation on the Lupus Anticoagulant and the INR being off. But here is the Link to the article: http://www.annals.org/cgi/content/full/127/3/177. So do what you need to do with it. :)

Eponym & history
We should add the fact that this test was initially developed by Armand Quick. JFW | T@lk  17:10, 1 June 2006 (UTC)
 * Definitely, I still remember forms that said PTT (Quick's test) on them! -- Samir   धर्म 01:38, 3 June 2006 (UTC)

That would have been incorrect :-). JFW | T@lk  20:17, 5 June 2006 (UTC)

Google
This page is number 4 on Google for "prothrombin time". Nice one. JFW | T@lk  20:18, 5 June 2006 (UTC)

Help for Citation re: LAC
Hi I am not sure how to add this citation on the Lupus Anticoagulant and the INR being off. But here is the Link to the article: http://www.annals.org/cgi/content/full/127/3/177. So do what you need to do with it. :)

Quick reference - the big lie
Countless articles refer to Quick's 1935 paper in J Biol Chem 109:73-4. Slight problem: J Biol Chem is fully available online, and the article doesn't seem to exist! I'd love to do some sleuthing, but somebody must have made up this reference!

Instead, I found Quick himself referring to the Am J Med Sci article from 1935 which is similarly titled but probably exists (as opposed to the J Biol Chem article). How on earth could this have happened? JFW | T@lk  21:58, 9 November 2006 (UTC)


 * a few sources cite it as J Biol Chem 109:LXXIII... Maybe the roman numerals mean that there was a separately paginated part in/of that issue (not available online)??
 * Hmm... While Quick did have several papers in the Journal of Biological Chemistry, and several of them did relate to prothrombin, none of them are the reference you mentioned.  There is quite a bit of confusion about this reference from nearly everyone who cites it in a paper...   Everything from April OR May of 1935, and 'roman numerals' of LXXIII to XXIII.   Since so many sources use the citation, I'm inclined to believe that this is in a supplement that the journal put out between April and May of 1935, which may account for all the citation confusion for this article:
 * The prothrombin in hemophilia and in obstructive jaundice.
 * Quick AJ
 * Journal of Biological Chemistry, 1935; 109: 73-74.
 * Now, that being said, you can find this reference:
 * A study of the coagulation defect in hemophilia and in jaundice.
 * Quick AJ, Stanley-Brown M, Bancroft FW
 * American Journal of the Medical Sciences, 1935; 190(4): 501-511.
 * And additionally these other references which Web of Science says are highly cited:
 * 1) On the relationship between complement and prothrombin
 * Quick AJ
 * Journal of Immunology, Aug 1935; 29(2): 87-97
 * 2) Determination of prothrombin
 * Quick AJ
 * Proceedings of the Society for Experimental Biology and Medicine, Dec 1939; 42(3): 788-789
 * Someone who has access to these journals (most likely paper versions since these references are older) should check these references...  Any takers?  —Preceding unsigned comment added by 128.227.98.109 (talk) 03:19, 10 December 2009 (UTC)

=
I looked this up yesterday (21Nov10). The correct reference is JBC 109: lxxiii. This is an abstract from the Proceedings of the American Society of Biological Chemists for the 29th meeting in April 1935, and these abstracts are bound in volume 109 of JBC after the last issue for that year. Its no lie; you can easily see where the lxxiii would have mistakenly represented as 73.

Liver disease
Despite being first described in liver disease, the PT is losing ground as a measure of severity, see JFW |  T@lk  22:56, 23 June 2007 (UTC)

Quick
I have found a nice historical reference by Quick himself:


 * http://circ.ahajournals.org/cgi/reprint/19/1/92

Will work it into the article soon. JFW | T@lk  07:50, 26 December 2007 (UTC)

Normal Range?
Prothrombin Normal Range 16 - 18 seconds ::

Why are two different normal ranges listed, first 0.8-1.2 and then 0.9-1.3? One of these is obviously wrong. Based on the formula given, it seems that a result of 1 corresponds to the mean of the control group. Assuming a normal distribution, this would make the range 0.8-1.2 the likelier candidate since it is symmetrical about the number 1. Neoprote (talk) 12:54, 20 May 2008 (UTC)

Confused about Methodology
Is it the blood or the plasma that clots?

"The plasma is analyzed by a medical technologist on an automated instrument at 37°C, which takes a sample of the plasma. An excess of calcium is added (thereby reversing the effects of citrate), which enables the blood to clot again." Horus (talk) 21:43, 14 March 2009 (UTC)

Prothrombine results just in...
I was just called by a staff member (nurse? assistant?) in my doctor's office; she informed me that the results of one of three blood tests--one for Prothrombin--was unusually high, and that I should consult a urological surgeon and/or a cardiovascular surgeon (references were provided). I asked her for the results, and she said, "39.4" I asked her what was "normal," and she said, "9-to-11."

I then asked her what the test was for, since it had not been explained to me the previous week during my visit to the doctor (I am a prostate cancer patient; post-surgical PSA: 0.1, and am on coumiden for DVT). She said she didn't know. That's why I'm online here...what does it mean to have a score of 39.4 versus a preferable range of 9-11? I don't even know exactly why my physician ordered the test.

Ron Colburn Anthem, Arizona 72.204.251.9 (talk) 00:24, 13 January 2010 (UTC)

PT pathway?
Is the PT and aPTT but down wrong. Ie PT should be intrinsic and aPTT extrinsic. Factors 8 and 9 are essential to extrinsic pathway eg in haemophilia and they result in prolonged aPTT but normal PT...

Confusion about samples and sample summaries
In the statement "The INR is the ratio of a patient's prothrombin time to a normal (control) sample, raised to the power of the ISI" there is ambiguity. One doesn't take a ratio of one measurement to a "sample" which contains measurements on multiple subjects. Usually what is meant is a summary of the sample of controls. Which summary is used is quite arbitrary - mean, median, 95th percentile, etc. I would appreciate some discussion on this point. 174.50.218.189 (talk) 23:45, 5 June 2011 (UTC)

PT v. INR
The initial paragraph says this test is also called "Protime INR" and "INR PT". This is incorrect. The test is called Prothrombin Time, Pro-Time, or PT. The RESULTS are reported as an INR. Might be splitting hairs, but as a clinician, this gets a bit tricky. Order a "INR" and a snarky lab tech calls and says "There's no such test as an INR, do you want a Protime?". PIA, but true. Teaching students to write it the correct way is a constant irritation. It is often written as a PT/INR, although the "INR" is completely superfluous. I think this paragraph should be re-written to better explain the PT/INR nomenclature. Understood that most people now REFER to it as "getting an INR" or "drawing an INR", this is not how it's actually run. I'd like some thoughts before i re-write it. BBODO (talk) 19:08, 4 September 2012 (UTC)
 * And reliable sources use the vocab in the way you're suggesting, right? Biosthmors (talk) 19:19, 4 September 2012 (UTC)
 * Because it sounds like a good idea on the face of it. Biosthmors (talk) 19:37, 4 September 2012 (UTC)

I'm sorry, i don't understand the comments. BBODO (talk) 03:48, 6 September 2012 (UTC)
 * No problem. I'll try again. Your ideas mimick the words and phrases used by reliable sources, right? Biosthmors (talk) 17:10, 6 September 2012 (UTC)
 * Well that kind of mimicks my previous wording. You aren't suggesting we adopt a new way of wording things that isn't used by reliable sources, right? All I'm asking is that these things be verifiable. Biosthmors (talk) 17:20, 6 September 2012 (UTC)

Low importance?
I see this article is rated "low importance". But to those of us on anticoagulation therapy, knowing what the INR means is anything but "low importance". If the INR is subtherapeutic for our condition, fatal blood clots could form. If it is supertherapeutic, fatal hemorrhage could result. I have experienced both. I had a microstroke when my INR dipped to 2.5, and required 8 units of blood when I hemorrhaged after surgery (as they were reintroducing Coumadin, they were careless in their monitoring and my INR hit 9.5; they suctioned 3.5L of blood from my abdominal cavity). So understanding INR is truly a matter of life and death. An informed patient can remain a live patient.

Jmnewcomer (talk) 06:48, 7 April 2013 (UTC)

Usual ISI values?
The article says usual values are 2.0-3.0 which I consider wildly off - should be more like 1.0-1.4 Any source at hand? Richiez (talk) 20:49, 2 July 2016 (UTC)

Draft:Fiix prothrombin time
Please consider incorporating material from the above draft submission into this article. Drafts are eligible for deletion after 6 months of inactivity. See Wikipedia_talk:WikiProject_Medicine/Archive_135 for specific suggestions. ~Kvng (talk) 00:20, 29 October 2020 (UTC)