TB Test?

[pmarank]

Hey guys Im just kind of confused about TB tests and I thought that you guys were probably knowledgeable on the subject. So I took a 1 step TB test last year, to work at a hospital, and it came out positive. I dont really know what that means but then they took a chest x-ray and I was able to volunteer.

What does a positive result mean? The nurse that confirmed the results then told me that I should never have another TB test in my life but the new hospital I am trying to volunteer at requires a 2 step TB test. So does a positive result mean that I shouldn't have another TB test done?

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[HatWobble]

Hey guys Im just kind of confused about TB tests and I thought that you guys were probably knowledgeable on the subject. So I took a 1 step TB test last year, to work at a hospital, and it came out positive. I dont really know what that means but then they took a chest x-ray and I was able to volunteer.

What does a positive result mean? The nurse that confirmed the results then told me that I should never have another TB test in my life but the new hospital I am trying to volunteer at requires a 2 step TB test. So does a positive result mean that I shouldn't have another TB test done?

A positive result means you have antibodies against TB in your system. Were you born in the United States? If not, you may have been vaccinated against TB when you were young. If so, you may have been exposed to TB. You don't need to get a PPD skin test anymore because the result will always be positive. Tell the new hospital that you have a history of positive PPD-- they will ask you to get a CXR or, alternatively, you could get a copy of the one from your previous hospital.

 

[nadaba]

Hey guys Im just kind of confused about TB tests and I thought that you guys were probably knowledgeable on the subject. So I took a 1 step TB test last year, to work at a hospital, and it came out positive. I dont really know what that means but then they took a chest x-ray and I was able to volunteer.

What does a positive result mean? The nurse that confirmed the results then told me that I should never have another TB test in my life but the new hospital I am trying to volunteer at requires a 2 step TB test. So does a positive result mean that I shouldn't have another TB test done?

This is going to be your proof now. Generally, you will only need to get an X-ray every couple of years, and you can have your doc forward the results to whoever needs it.

I had a positive test 10+ years ago, took the medication, and moved on.

(I hope this post isn't considered medical advice? )

 

[HatWobble]

(I hope this post isn't considered medical advice? )

Ain't nothin' you can't find on the CDC website.

 

[Caesar]

what you should or shouldn't do is up to you and your physician. You can't solicit that advice here.

I am leaving the thread open to discuss the information about a +TB test and other people's experiences.

 

[pmarank]

what you should or shouldn't do is up to you and your physician. You can't solicit that advice here.

I am leaving the thread open to discuss the information about a +TB test and other people's experiences.

lol thanks. I was really just trying to figure out what the results meant. I think Im just going to get a copy of that chest x ray and send it to the new hospital and see what they say.

 

[pmarank]

On a side note, why don't they vaccinate against TB in the US?

 

[goobears]

On a side note, why don't they vaccinate against TB in the US?

Because TB isn't as prevalent in the US and the vaccine (BCG) isn't as effective.

 

[Bacchus]

This is just semantics, but I did a pulmonology rotation so I feel like I have to say it, since I was threatened a failure if I ever said someone was "exposed."

If you have a positive test you were either vaccinated or infected by TB. Exposed downplays the infection and gives patients a false, "Eh, so what."

 

[CopaceticOne]

On a side note, why don't they vaccinate against TB in the US?

Well, if people in the US were routinely vaccinated then we would loose the surveillance capabilities of the TB test because most people would have reactive antibodies in their system. As a result, everyone who needed a TB test would require a chest x-ray versus a simple skin test. As mentioned earlier, since TB isn't prevalent in the USA, it is more efficient for our healthcare system to use the skin test for detection. If you want to learn more, I highly recommend a course in immunology.

 

[KTD]

The vaccine only prevents severe manifestations of the disease in children (meningitis for example) not TB in general. In areas where TB is endemic, children are vaccinated but in countries like the US where young children are not exposed to the disease the vaccine is pointless. Also, apparently after the BCG vaccine your PPD test is only positive for 3-5 years, not forever.

 

[Camy99]

Nah it's longer than 3-5 years. I had it done as a child outside the US, and just earlier this year (like 10yrs later) it was positive with negative chest xray.

But yeah, OP just immediately tell the hospital that you were vaccinated and forward them a copy of the xray

 

[Kalamazoo]

I had funky results from a TB skin test twice. The physicians said they looked positive at first glance, but technically they weren't. I think they just irritated the s**t out of my skin. Now I just request to have a blood draw rather than having the skin test done.

 

[pkwraith]

There is a chance that you may return to a negative TB test as you get older, but I wouldn't hold my breath on it.

Chest XRays are good for two years normally. Keep good record of your positive TB test, and ensuing chest xrays. You'll probably need them later. Sometimes, health providers still want to do a skin test before chest xray, and if you have a good history of documentation, you can get them to skip past the skin test.

This year, I did the quantiferon gold for TB (which doesn't have the issue with previous vaccination), which is much more convenient than chest xrays (and covered by my insurance, so why not). That seems like a better alternative when you need a TB test, and you should bring that up with your physician when you need your next TB test.

 

[ppfizenm]

Hey guys Im just kind of confused about TB tests and I thought that you guys were probably knowledgeable on the subject. So I took a 1 step TB test last year, to work at a hospital, and it came out positive. I dont really know what that means but then they took a chest x-ray and I was able to volunteer.

What does a positive result mean? The nurse that confirmed the results then told me that I should never have another TB test in my life but the new hospital I am trying to volunteer at requires a 2 step TB test. So does a positive result mean that I shouldn't have another TB test done?

HIV can sometimes cause a positive reaction to a ppd. Did you get tested afterwards?

nevermind. pretty sure it's the other way around. HIV can cause a false negative.

 

[link2swim06]

Having a positive PPD means very little...its actually a pretty low specificity test...meaning lots of false positives, and it isnt even exactly testing FOR tb.

There is a new blood test called a quanti-feron gold test which can be used instead of the PPD test. Most physicians that are update to date with PPD testing will order a quanti-feron gold test, if it is positive you generally get 6 months of antibiotics, if it negative then you dont do anything.

Granted even a positive quanti-feron gold can have false positives from a few other bugs, but it is leagues better than the PPD.

I am speaking from experience and its really NOT big deal, just follow up on it. Get the blood test, it cost like $60 and move on from there.

FYI dont get the PPD ever again, you are always going to test positive and the reaction will just keep getting worse.

 

[link2swim06]

This is just semantics, but I did a pulmonology rotation so I feel like I have to say it, since I was threatened a failure if I ever said someone was "exposed."

If you have a positive test you were either vaccinated or infected by TB. Exposed downplays the infection and gives patients a false, "Eh, so what."

No... because explain how I am NOT vaccinated, CLEARLY positive PPD, and NEGATIVE quanti-feron gold (meaning no TB...assuming the higher specificity test trumps the lower specificity test). In other words, remember the possibility of false positive with any test, esp with this test.

 

[Bacchus]

No... because explain how I am NOT vaccinated, CLEARLY positive PPD, and NEGATIVE quanti-feron gold (meaning no TB...assuming the higher specificity test trumps the lower specificity test). In other words, remember the possibility of false positive with any test, esp with this test.

Take it up with my attending haha. Perhaps I don't remember the story 100% correctly.

 

[hot sauce]

If you haven't already then you should speak to your physician about this.

With all due respect to nurses they are not qualified to discuss this topic. Saying you should never get tested again may not be correct.

In some cases, (I do not know the details of your case and cannot give you advice) a positive TB test can be an indication to treat with INH (even with a negative cxr); it depends on the clinical picture. I am not even sure what test you had when you say a 1 step test. It may be worth getting the QFT-G test but again that is a decision that needs to be made by your doctor.

Bottom line - see your doctor. A negative cxr may be enough to allow you to volunteer but this may (or may not) need further followup.

 

[hot sauce]

No... because explain how I am NOT vaccinated, CLEARLY positive PPD, and NEGATIVE quanti-feron gold (meaning no TB...assuming the higher specificity test trumps the lower specificity test). In other words, remember the possibility of false positive with any test, esp with this test.

Of course there are false positives and of course there are false negatives (I don't know the sensitivity of quantiferon).

Also, I have seen PPDs incorrectly interpreted - you should measure induration and not redness. Often when a patient is tested the pretest probability is high enough that it is worth treating (but when used for screening the picture may be different) - again hard to judge without the entire picture (prior PPD, exposure risk, immune status, ect). So a positive PPD and negative quantiferon have a number of possible explanations some involving the patient having latent TB and some not (of course if you order the quantiferon after a +PPD and then treat if negative one would have to wonder why you got the second test)

 

[bunnity]

You can get a positive PPD if you have been infected with another mycobacterium with a similar antigen... the antigen injected in the PPD is not unique to mycobacterium tuberculosis (another reason for false positives besides previous BCG vaccination).

 

[druggeek]

HIV can sometimes cause a positive reaction to a ppd. Did you get tested afterwards?

nevermind. pretty sure it's the other way around. HIV can cause a false negative.

>15mm on the skin is almost guaranteeing a negative HIV result cause basically your immunte system is functioning extremely well

<5mm + HIV positive test = positive TB test because youre shut down almost


OP, I wouldnt over worry about this positive test. If you've had the BCG... odds are it's from that. In Canada, the BCG can be used to rule out a positive test for the most part (not in the US though which leads to false diagnosis). If you don't live (or travelled to) in a higher infected area, nothing to worry about really.