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Tests for TB - Online Doctor Chats

Date : 21-Feb-2012
User rating for this question
Very Good Posted in: Lung and Chest disorders
Answered by

General & Family Physician
Practicing since : 2009
Answered : 584 Questions
User :   i took a ppd skin test for tb 2 days ago and gotten my results today. well the result came out positive but my chest x ray was taken and test is negative (lungs are clear and fine). I was being told to take isoniazid for 8 months for prophylaxis treatment. but what i am concerned about is I am a medical student and I know how the test is being given, when the doctor took my ppd exam, i did not see a wheal at all and right after the test he covered the area with a bandaid. as far as i know wheal is supposed to form and stay atleast 3-4 hrs and there should not be bandaid given. before i started taking INH which can cause liver problems, will I be able to take another skin test just to make sure the previous one was not false positive or the doctor was wrong in giving the shot? but i read it online once u take a skin test, you should not take because it will always reamain positive, i understand that but i really feel that the test is false positive and by the way it didnt produce a wheal and he used a bandaid on that place right after the shot? please can anyone answer because before i start taking the isonizid , i want to make sure i have latent infection. also is isoniazid really necessary, the doctor is like highly recommended but nor required. please help if you can
User :   hello
Doctor :   Hi,
Doctor :   Dr XXX here
User :   hello dr.
User :   did you get my msg?
Doctor :   Please give me a minute to read your post
User :   ok
Doctor :   As you are a medical student , may i know since how long are you exposed to the patients ?
User :   well i am a student meaning i just comlpeted my first 2 yrs
User :   i have not started my clinical rotations yet
User :   i live in XXX
Doctor :   ok,
Doctor :   Al most al adults do have the TB bacilli residing in the body
User :   i have taken a test with ppd 3 -4 yrs back when in undergrad and it was negative than , i took this test because before you start the clinical rotatin ..
User :   okay..
Doctor :   but not in sufficient num to cause the clinical symptoms
User :   so i was just wondering, shouold i take the inh therapy for prophylaxis becuse i know it can have side effects?
Doctor :   or even the immune system is able to constraint them if healthy
User :   and as i said the wheal did not form when he inserter the injection and
User :   could it be wrong?
Doctor :   i do not see any need for the prophylaxis
User :   ohh ok...
User :   i understand diff poeple has diff views
User :   but do you thikn
User :   can i get another test done?
Doctor :   and the Mountoux test will be positive in 80 to 90 5 of adults
User :   is that okay, because i really think the test was taken wrongly. is it okay to get another ppd test on the other arm ?
Doctor :   its not a good test to know the Tb status in adults
Doctor :   i see there is no need of another test
User :   so even in the future, if i need a ppd test, i should never get that done correct?
User :   i should always get chest x ray right?
Doctor :   if you want to get TB ruled out get a Tb PCR test that will rule out the active infection
Doctor :   yes, you may never need ppd
User :   ok so every time im required to take the test
User :   i need chest x ray to rule out correxcct?
Doctor :   but xray will show findings in a full blown active TB infection in the lungs only
User :   yah i took lung x ray and it was clear...
User :   so i wont need to take Isoniazid correct?
Doctor :   Tb will not affect the lungs alone
Doctor :   hence TB PCR would be a gold standard test
User :   is this expensive?
Doctor :   NO , need of taking the prophylaxis unless ruled out TB PCR
Doctor :   no its not too expensive
Doctor :   but the cost of it differs from lab to lab
User :   ok thank you
Doctor :   Thanks for consulting me
User :   so just bc my lung
User :   are clear
User :   it doesnt rule out
User :   that i dont have active tb
Doctor :   yes
User :   ok thank yyou doctor
Doctor :   Is there anything i can help you with ?
Doctor :   Are you there ?
Doctor :   I have to close the window as you are not responding. Please chat with our doctors 24/7 for medical queries.
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