QuantiFERON-TB Gold was positive

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Mary, a senior female, had a followup appt with her PCP today. PCP is young, inexperienced but trying to do things the right way.

Mary had labs done for a rheumatologist. Quite comprehensive, but a couple surprises. She had a positive result for IgG P41 (Borrelia) on Lyme Test. It was the only Lyme antibodies positive, yet called false positive(she had the bullseye rash in the early 80’s).

Other surprise is that the QuantiFERON-TB Gold was positive. It is an indication of latent/sleeping TB. Not active, but enough activity to create antibodies. She has no known TB exposure. PCP presumes this test is not a false positive because it is the “gold standard”, the deciding factor after a positive skin test and chest X-ray. Dr is already talking about reporting to CDC, Public Health nurse to monitor antibiotics, etc.

Dr has ordered chest X-ray to determine if active or latent TB. Also ordered HIV test because drugs used to treat latent TB appear to be a problem for people with HIV.

Is a positive QuantiFERON-TB Gold result common for ME/CFS/Fibro? What encouragement can I give Mary? Any hope for a false positive? Mary is very private person who doesn’t enjoy visitors in her home. Any alternatives for public health nurse home visit?
 

Gingergrrl

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Is a positive QuantiFERON-TB Gold result common for ME/CFS/Fibro? What encouragement can I give Mary? Any hope for a false positive?
This is a long-shot but has Mary ever had IVIG which can cause a temporary false positive for antibodies that are not really hers? IVIG can cause things to show up on blood tests temporarily that are like "passive immunity" from the IgG of the donors but it is not real. I had a temporary "indeterminate" result on a Quantiferon Gold blood test (not positive but "indeterminate") in 2016 b/c it was done too close in time to an IVIG infusion (back at that time).
 
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This is a long-shot but has Mary ever had IVIG which can cause a temporary false positive for antibodies that are not really hers? IVIG can cause things to show up on blood tests temporarily that are like "passive immunity" from the IgG of the donors but it is not real.

A good thought, but Mary (not her real name of course ) hasn’t had IVIG.

Thanks! 🙂
 
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QuantiFERON-TB Gold Plus uses a 4 tube process to test TB antigens in CD4 and CD8 immune cells. One of my concerns about false positives is tied in with their disclaimer....

From a brochure distributed by Qiagen discussing false negatives...
Disclaimer: The performance of the USA format of the QFT test has not been extensively evaluated with specimens from individuals who have impaired or altered immune functions, such as those who have HIV infection or AIDS.

Am I right in thinking that HIV individuals have decreased CD4 activity? And that some ME/CFS individuals have altered CD8 immune functions? Higher?

The company acknowledges there are at least 3 other Mycobacteria that can cause false positives.

Another concern is for people with agglutination sensitivities caused by lectins....the Mitogen control tube contains lectins. If a person is already reacting to lectins, will the control tube ‘over-react’? That would raise the control number and skew the results positive.

Also from Qiagen brochure...

Why do you include a positive control? How does this work?
The Mitogen tube is used as an IFN-γ positive control for each specimen tested. The Mitogen tube also serves as a control for correct blood handling and incubation. The mitogen used is phytohaemagglutinin-P (PHA), which is a non- specific stimulator of T-cells. While it is a direct activator of T-cells, unpublished data suggest that macrophages are also required for it to activate T-cells.


Phytohaemagglutinin-P is a lectin from kidney beans per Wikipedia.
 

Strawberry

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This may or may not have absolutely nothing to do with this thread. But I tested positive for TB as a small child, but that was 40+ years ago and not by the QuantiFERON-TB Gold blood test. I have thought of that test (and the resulting 12 or 18 months of antibiotics) and wondered if it had anything to do with my current ME/CFS... No one in my family or surrounding friends have EVER tested positive. So why did I?

I also find it mildly amusing that doctors knowing I tested positive for TB have never once given me a chest xray as an adult. I haven't had one since I was diagnosed at age 10!

Best of luck to Mary
 
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An update on ”Mary”. After several months, Mary was tested again using the T-Spot test available locally at Quest, but not avail at LabCorp. The new test was negative. Chest X-ray early in 2020 was negative. Her rheumatologist has indicated in people with high rates of inflammation the QuantiFERON-TB Gold...he has seen many false positive results. Some sources indicate that T-Spot is used as the retest alternative for hospital workers. Mary is happy with her results.

Is there a clue for us in Mary’s false positive .... years (decades) ago I learned in one of my college classes not to eat undercooked kidney beans because it damages red blood cells. No specifics on the damage was given, but the nutrition professor indicated it was based on research (possibly done in the 1950’s or 60’s). Is it possible that our red blood cell irregularities is actually an allergic reaction to kidney beans/lectins run amuck? 🤓🤓🤓