Hemostasis: Lesson 4 - Tests (INR, PTT, platelets, fibrinogen, D-dimer)

A review of the measurement and interpretation of platelet count, INR, PTT, fibrinogen, d-dimer, and the mixing study.

[@StrongMed]

Erratum: @8:37, as pointed out by a viewer, somewhat unexpectedly Factor XIII deficiency does not cause abnormalities of either PT or aPTT. In fact, the presence of a clinical bleeding disorder despite normal PT, aPTT, and tests for vWD is an indication to *consider* checking for XIII activity (though this test is not available in many locations).

[@jjsanchezramirez]

I know this is a 9 year old video, but as a Pathology resident studying coagulation testing, this video is gold.

[@bigdog4574]

You, sir, are a Life Saver on so many levels! Thank You!

[@brycepasko3854]

Your videos are excellent! I teach coag to my residents and fellows and will be sending them to your channel for a thorough review. As an aside, Thrombin Time is not generally ordered on the wards, however, it is frequently reflexed in the coag lab as a screen for heparin prior to performing a standard mixing study. Another point, I do think it is worth having discussions with surgeons prior to ordering PT/aPTT testing for patients with no personal or family history of bleeding prior to surgery, as this could be one of the first steps in reducing unnecessary plasma transfusions and their associated risks in otherwise healthy patients (we all have a story of a healthy patient getting plasma prior to a procedure for a lab abnormality with no personal/family hx of bleeding then ending up in the ICU or worse with TRALI). Keep up the excellent work!

[@zarointl]

I first listened just to review platelet structure and physiology. I have been watching and listening at my desk for tw hours now. THANKS! I will be referring your videos to my students. :)

[@BaronVonDousel]

I love the series have an exam on haematology and transfusion on Monday. Wish this series was finished before the exam. Fantastic teaching Eric, many thanks.

[@gpbadwal14]

Best lectures on the topic as alwyas....waiting for next parts....thankyou eric...u r an awesome teacher...

[@CityofLadies]

This series is wonderful!

[@blade15c]

As a surgeon, I appreciate this lesson refresher. And your last statement 😄

[@svdaedalus]

Thanks for that. Excellent explanation, as always. I always get frustrated when I (commonly) hear residents freaking out when a patient w/ alcoholic liver disease has an elevated INR. The literature supports what you said, that these patients can, in fact, be hypercoagulable. And of course, as far as I know, the INR has only been validated for monitoring warfarin therapy, not in predicting bleeding risk in patient w/ advanced liver disease. I've even heard from some hematologists that fibrinogen would probably be a better test in these patients, absent thermoelastography (TEG or ROTEM), which I guess, are expensive and (still) rarely available.

[@StrongMed]

Thanks for the feedback! The INR was developed specifically for monitoring coumadin, and I agree that's its most appropriate use. It's also used as part of the MELD score for end-stage liver disease, which is also appropriate, as long as people realize that an elevated INR in that population is only a marker of severity of liver disease, and not an indicator of bleeding risk. I haven't personally come across a hematologist advocating for use of fibrinogen for assessing bleeding risk in these patients, but at least at first glance, I would guess that it is better. I'm only familiar with TEG's existence, and know very little about it - not available at my institution.

[@BalaBala-zu3fk]

"

[@Malhiu]

Thanks, Eric. I have seen INRs differ lab to lab, within lab for two separate samples in my patients on warfarin. However, I've not seen difference in results by more than 20% which can be huge if INR's over 2.5. I eagerly await your rest of the videos on this topic.

[@thaole2203]

Thank you very much. I love all of your lectures.

[@meryemlahbara9669]

Thank you very much .. I did hematology like 6 months ago .. & this is a good reminder for my Clinicals ..

[@houseofleadership124]

Very well organized easy to understand video. Best lectures on the topic as alwyas....waiting for next parts....thankyou eric...u r an awesome teacher...

[@lalrinchhanaralte9969]

Salute to you Sir. Your videos gave me not only knowledge but a way to approach problems on a more practical aspect. Please make more videos

[@Kami-yb4uj]

excellently and comprehensively presented.

[@hernan625]

I'm really thankfull Eric, and I'm starting to love hematology, you should make more lectures about it like approach to anemia, hemorragic syndrome, trombosis, hypercoagulability

[@StrongMed]

hernan625 I'm glad you like the videos. Those topics are all coming up this year.

[@sunving]

Thank you very much , I suddenly seem to get more out of it this time , your lecture is superb. I heard and read this topic many time in my life but I never remember much out of it. Your lectures is great great.

[@xDomglmao]

When KZbin suggested this video I was literally kissing my hands and doing a "My savior" gesture.

[@Kittyququmber]

Very well organized easy to understand video. In fact the whole series is like this!!

[@drparagkumar]

Loved it. Preparing for Pediatric Hospital Medicine Boards 2019. Thx

[@miradakangahnp5605]

Thank you Dr. Eric.

[@loveeveryone1377]

it was a great explanation of the coagulation tests, thank you. It would have been nice to hear about effects of contamination on the test results and how to identify it.

[@geofmali]

ya this is helping. keep it up. third yr stud malawi college of medicine

[@davidhersey1577]

Very well done. I recommended many of your video to my colleagues.

[@sunving]

Thank you very much Dr Strong. ,very good lecture.

[@nashelsegrenville7984]

Thank you very much for this. I am a third year Med Tech student and this will surely help me with my finals this week.

[@NoAnimosity91]

I'm in a Med Tech program now! Almost finals time and I'm so stressed! How do you like the job?

[@nashelsegrenville7984]

it's great! I'm the Quality Manager for this lab and I'm loving it!

[@ethanhelena1fan739]

Nashelse Grenville what school?

[@h.a7688]

Thank you GOD bless you... I was enlightened by this video

[@DomiPordeus]

Thank you so much for this video!

[@drstrange6892]

Such a great video Thank you sir 🙏🙏🙏

[@zareenafreenkhan2834]

very informative. good prep for ISH(ASCP)

[@thomassmith5639]

Great video! Thank you.

[@tinkageorgewilliam871]

Sounds like the guy I learnt x-ray interpretation from :) Nice video lad.

[@jakec7609]

great lectures. thank you

[@Adelaide621]

SUPER HELPFUL. Thank you

[@mrabin8098]

very good explanation ever!!!

[@lester_ernesto]

Awesome !! Thanks for sharing Doctor ;p

[@mariociencia12]

Very nice video! I would like to know more about INR. For example: Why the control PT is a geometric mean and not an arithmetic mean? It has some relation to a log scale? Why ISI is an exponent? How exactly is ISI obtained? I think this magnificent series about hemostasis deserves a more detailed video about INR and ISI. Please, at least inform to me where exactly I could get answers for my questions

[@AyazSamo]

Wonderful Hematology! Things I never know before! Keep it up. Respects from Sindh, Pakistan

[@ajmalnayyar2254]

Do you have any updated lecture on Throbmoelastometry and role of ROTEM device in acute bleeding management as POCT?

[@kaledaanwar5465]

great presentation

[@owenkottoh8559]

Great presentation

[@nsas955]

very great discussion

[@user-tm7qf6zi1l]

thanks doctor....thanks...thanks

[@zedawing]

Thank God For You!

[@ameliaedwardlucas828]

I have serious coagulation disorder. And this video help me much to learn how blood is formed and works. Thank you

[@danielleg2616]

Do you have high to Ddimer

[@ameliaedwardlucas828]

@@danielleg2616 I don't know what really happened but there were lots of bruises all over my body. my nose, ears and mouth are bleeding

[@danielleg2616]

@@ameliaedwardlucas828 🙏

[@abh3835]

Informative sir... Thank you so much

[@RR-kn1kb]

Thanksssssssss you saved my life

[@barshathapa3208]

was really helpful,,,, thank you sir!! :)

[@tracytorres8850]

We test the thrombin time routinely in our clotting screen in the UK, it would be great if you covered the thrombin time also. thanks

[@porcupineinstincts6675]

yes. and ive found TT to be a strong indicator for increased Fibrinogen

[@J2J_Trini]

Almost all lab test ranges are affected by each new generation or lot number, you can always ask the laboratory to print these numbers along with the aptt test to identify when these changes are made.....

[@salsabilwayz8584]

Thank you so much sir!

[@DocHemulin]

Hello Dr. Strong, I was wondering the the antiphospholipid antibodies do not prolong the PT also ? as I understood they interfere with the phospholipids (which are also crucial in the PT test).

[@brentjgambill3846]

I don't know about what it does or doesn't do but I have Anti-Phospholipid-Syndrome lupus Anticoagulant and I take a PT- INR test every two weeks

[@munta_ali]

very simple and informative thanx

[@reeeeeeb]

Hi Eric. Thanks so much for your videos, they are incredibly helpful. Just out of curiosity: you mentioned you've heard of anyone requesting the TCT, I can only assume this is said from a pre-dabigatran point of view? If not how does the American system test for dabigatran? Or is the drug simply still not used there? Thanks again, and keep up the fantastic work.

[@StrongMed]

reeeeeeb In the US, dabigatran use has rapidly grown in the past several years, but levels are not monitored (though perhaps they should be!). A good scientific review of the relevant issues is here: www-ncbi-nlm-nih-gov.laneproxy.stanford.edu/pubmed/25994994. And a good review of the history and politics of why dabigatran is not monitored is here: www.medpagetoday.com/Cardiology/Arrhythmias/46901.

[@dr.mosabgaafar6066]

Thanks

[@angminhuc5578]

Thank you very much for the useful video!!! I just realized why do they still use aPTT to test the effects of unfractionated Heparin instead of some more precise measure?

[@strawberryheart6582]

hi.! thanks for the videos.. but can you provide your references, coz i plan to cite them in my term paper

[@rajkumarm1557]

Excellent

[@Joshsinterestingvids]

Saved my ass for my MLS exam. Thanks man.

[@photon99]

This is helping me so much for my MLT exam too!

[@user-cu8et7tm2u]

Low fibrinogen level may be seen in: Congenital or Acquired Hypofibrinogenemia Disseminated Intravascular Coagulation (DIC) Afibrinogenemia Dysfibrinogenemia Fibrinolytic therapy

[@melduterte6102]

Thank you

[@87babak]

thank you :)

[@jimin4life797]

Dear Eric i would like to ask you if you would mind me converting your video to mp4 and cutting it and posting it to youtube. Of course i will give you the credits for it but i need it cut because i have to do a presentation in pathology and i have to explain each test with text and video separated please answer me as soon as possible

[@hinagulzar740]

Amazing👌

[@etomidateem222]

thank you.

[@lanaa198]

Perfect thanks

[@histephenson007]

Good job

[@AftabAhmed-rr4ru]

nice learning video

[@M7mmad08]

You are genius

[@clydethrift4817]

How long does it take to get the results for a factor level test?

[@StrongMed]

It depends on the specific test, and the lab that's being used.

[@leila9347]

How to get Tp with %

[@DocHemulin]

Hi Dr. Strong, how come the PTT can be normal in advanced liver disease and is the D-dimer always increased in such a state? Why is liver disease associated with increased levels of vWF? and lastly-why vitamin K defficiency doesn't prolong the PTT? (you didn't mention it as a cause in the list) Thanks!!

[@porcupineinstincts6675]

sorry but i dont think he said any of those..?

[@DocHemulin]

He sure did. The PTT is shown in the table in 16:05, the increased vWF levels in minutre 22:26.

[@porcupineinstincts6675]

16:05- yes i was wrong..he did say that..now im noticing..well i believe it has something to do with that concept where initially no matter what goes wrong with the prolonged uncontrolled clotting times..it all happens also due to one of the fact that in such conditions the natural inhibition of clotting pathway is worn our..consumed or dis regulated by inflammatory cytokines and thrombin..which doesnt happen initially.. so sometimes means in the beginning aptt could be normal..same applies to DIC below in the table....what do you think?

[@porcupineinstincts6675]

22:26- Also Sir, wrt the vWF doubt..i think he should have mentioned that it could be because the inflammatory cytokines bring down the ADAMST13 levels which is responsible for cleavage of ultra large vWF...which is again released by the Weibel Palad bodies when the same inflammatory cytokines come in contact with the endothelial cells..hence u also see increased vWF at the same time when ADAMST13 is reduced..plz let me know if im wrong. Thank you.

[@thekitacat]

This is an error in the description of what the PT measures. It is stated that the PT measures Factor XIII (thirteen). It does not the PT measures Factor VII, X, V, II and I (fibrinogen) at time 8:37 approximately.

[@StrongMed]

You are correct. Thanks for pointing this out!

[@RinaPadvekar-rw2wx]

Nice

[@user-dz1wk9qm8g]

Explain d dimer and COVID, is there any relation,?? Is it linked?

[@meryemlahbara9669]

Fibrinogen at 13:19

[@meryemlahbara9669]

D Dîmer at 14:46

[@xavierxrc]

Wow. I think this is the best coagulation video I've seen.

[@markcullinane6833]

I think you should make it clear that thromboplastin is aka tissue factor...

[@johnvideovlogs]

Bro can you please upload video how to make for PT pooled for control

[@StrongMed]

If I am understanding your question correctly, you're asking how to determine the "normal range" for PT using a combination of blood from normal individuals and a specific lot of assay reagent? If so, that's a very niche question that is too far outside my expertise to comment on. Sorry I can't help.

[@alhibiribrahimserag8967]

Thanks so much Doctor Keep going Can you tell me from where you are ? Or where are you from? My greetings from SUNDA🇸🇩

[@StrongMed]

I'm an associate professor at Stanford University, located in California in the United States.

[@ghdsds]

This guy is the shit

[@user-mo1dh1xf2k]

Здесь описываются проблемы солнечных батарей которые я поставил 7 лет назад.

[@nellmarie98]

I HATE not being able to skip the lousy dove commercials before your videos. video number four will be my last video if the next one has dove as the sponsor.

[@CityofLadies]

The adds you get are targetted by youtube base on your demographics and depend on your browsing history. They are not decided by the person who runs the channel. #justsayin

[@germanmartinezcorral138]

Did you ever imagined you would be helping medical students way down south in the jungle of Colima, Mexico?

[@germanmartinezcorral138]

By the way I am that student, thank you so much!

[@StrongMed]

You are very welcome! I'm glad the videos have been helpful!

[@markcullinane6833]

I am a nobody

[@jadathompson506]

you sound like the voice from cat scratch :)