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Thursday, October 30, 2014
Untreated latent TB
My husband was exposed to TB while serving in the Armed Forces. He tested positive on a TB tine test in 1989 and was prescribed INH 4 months later. He doesn`t remember how long he took the medication but is sure it wasn`t over more than 2 months. His chest x-ray when he was prescribed the INH showed granulomas(sp) at that time. He has just recently been diagnosed with COPD, possibly emphysema. He also has more current x-rays also showing granulomas and has been told that he has some kind of restrictive lung disorder. My first question is: Can untreated/under-treated latent TB contribute to developing COPD? Secondly, we would like get him tested to be sure but he was told he should not have another TB tine test because he may have an adverse reaction to it given he has tested positive before. I know that there is another test but I am unclear if it would be safe for him to take it given the previous exposure. Thirdly, are there any studies suggesting that latent TB left untreated can cause heart problems? Thank you for your help.
Your question raises several interesting points regarding Tuberculosis screening and diagnosis. There are 3 reasons to believe your husband has had tuberculosis in the past:
1) Serving in the armed forces putting him at risk of being exposed to tuberculosis
2) A positive Tine test
3) Granulomas on chest x-ray
Based on your comments, he may not have had sufficient treatment. Improperly treated or undertreated tuberculosis may lead to recurrence of the disease and if unrecognized, lung scarring and damage. This can manifest clinically in the same manner as COPD with wheezing and shortness of breath.
The first step is to determine whether he currently has active tuberculosis. The likelihood is low given that only granulomas were present on x-ray and your husband (by your description) is not too symptomatic. However, it is prudent to ensure active disease is not present.
Active tuberculosis is most often diagnosed by examining at least three specimens of expectorated sputum (usually obtained first thing in the morning upon waking) for the organisms (mycobacterium tuberculosis). Alternatively, a single induced sputum performed in the clinic will suffice or a bronchoscopy performed by a respiratory specialist.
A recent chest x-ray should be performed to determine if the lungs appear worse compared to prior studies. Active tuberculosis almost always produces changes that are evident on chest x-ray.
If active tuberculosis is present, then clearly full drug therapy (at least 2 medications directed against mycobacterium tuberculosis, most likely 4 medications initially) is warranted. However, even if active tuberculosis is not present, several studies have demonstrated significant benefit in reducing the risk of reactivation of tuberculosis through full treatment with INH (70% reduction in risk or reactivation with 24 weeks of treatment, 93% reduction in risk with 52 weeks).
Heart problems are extremely rare in latent tuberculosis.
J Daryl Thornton, MD, MPH
Assistant Professor of Medicine
School of Medicine
Case Western Reserve University