Such a thing as false/positive TB quantiferon test

@dmk21 Welcome to Mayo Connect. I think your message got overlooked for a bit during the holiday, but I will try to answer you now.
As to whether there is such a thing as a false positive on this test, there is some evidence it can happen if one is exposed but not infected. That is why, even with a positive test, a lung x-rays is done before treatment is initiated.
I am going to make an assumption here, that if you are required to have an annual TB test, you work either in health care, in a job with high risk of exposure, or with immunocompromised people. If that is the case, state and federal regulations determine how long you will have to have a chest x-ray. Check with your state health department. By the way, someone in HR or your employee health office may just be automatically ordering it without checking the regs, so it would be a good idea to get the rules from the source.
Sue

Was quantiferon negative all 20 years except one time after the covid ?
I will look for an article i came accross few years ago and will upload here.
In regards to your question " will you ever not need an annual xray" - the answer is "it depends" each work setting has its own guidelines governed by Department of Public Health and Infectious Disease MD.
I would recconend finding their phone numbers and speaking to both. There should also be annual questionairre that we all do for tb surveilance/clearance that prompts our employee health departments for xrays, sputum tests, etc. If you are answering Yes to any if these questions, that might be another rrason why you need annual xrays.
In retrospective - we get 100 x more xrays just catching 45 min flight (SF to Los Angeles 🙂 than one signle chest xray. and At least you are not being asked for AFB sputum 🙂

Thank you for your reply. Yes my quantiferon has been negative for 20 years. I’ve never had any signs or symptoms of tb. I guess my next step would find an infectious disease doctor.

I am a healthcare worker of 30 years. I worked in a pvt hosptial for 25 years. The clientele was that of middle to upper class, and so was the area. When I tested positive, the pulmonologist worked in my hospital, was baffled like I was. That is why we both agreed to wait on treatment as the X-ray was negative and so was my 3 month and 6 month repeat quantiferon

Here is the article i was referring too.

Thank you so much!!! This article was very informative.

Good luck.
Your best bet is department of public health and an ID physician who "governs" TB guidelines.

You can also try to look up if thrre is anytjhing about Quantiferon being positive after Covid.
My scenario is a bit different. Mine was positive in 2008 after exposure, then subsequent negatives, yet after covid last June 2022 it was postive again. But I already did the treatment (took the pills) in 2021

I am very curious as to what quantiferon negative is? 78 years ago, I had a Tuberculin test that was positive, with a follow up chest Xray. As a child (18 months old) I had double pneumonia and my mother said I had scarring of my lung. But, when I started High School it was determined I had Tuberculosis, I was removed from my home, and placed in San Francisco General Tuberculosis Hospital for 3 months. l was then sent to Hassler Health Hospital for another 8 months. I was not allowed to leave my bed except to go to the bathroom, during all this time. I never had a positive sputum, even though I was tested monthly, and no change in chest x-ray or fluoroscope (which was also done monthly). I was 14 years old and lost 1 full year of school. I know today, there are medications to cure Tuberculosis and thus I am most interested in the above terminology.
Gina5009

If i understand it correct, Quantiferon (lab test) tests for exposure, not active tb.

Hello
My son tested positive for Quantiferon TB Gold Plus test. He had a BCG vaccine as a baby. His chest x ray normal. No symptoms either. He finished his leukemia treatment ab 1.5 yrs ago. I am baffelled how he caught this?
We travel overseas a lot. We were in Morocco for 8 months. Morocco is not a high risk country.
Could the test be false? Should we repeat it? His doctor is suggesting 3 months antibiotics for latent TB.

His blood test numbers:
Tb1 ag value 7.44
TB2 ag value 4.92
Nil value 0.10
Mitoyen value >10

Are these values high or low?

Any feedback is greatly appreciated
Thank you