Sunday, October 18, 2009
TB or not TB - that is the question
TB, tuberculosis, is a disease we see here all the time. It can affect almost any part of the body, but most often affects the lungs causing pulmonary TB. We don't have a blood test that can help us diagnose TB, so we rely on our clinical history, xray findings, and sputum samples, but there are problems with each of these. Histories aren't always accurate as patients don't always know when things started, and often answer questions about things that happened 10 yrs ago, when you are trying to ask them about now. The sputum sample is great if it is positive, but recently we haven't been able to trust either positive or negative results. The CXR had been what I would base most of my diagnosis on. There isn't one specific pattern on CXR that tells you pts have TB - it can be a patchy infiltrate, apical disease, or a white out with a pleural effusion. However I have seen a lot of TB here, and had felt fairly comfortable reading a CXR and saying if it looked like TB or not, until now. I saw this elderly man who presented with various complaints. His first CXR was normal, not suggestive of TB. When he came back 2 weeks later, I got another CXR as he wasn't getting better, and I couldn't believe the difference. In 2 wks time, this CXR went from nothing suggestive of TB to now, what easily could be TB. I chose to not start TB treatment, since there was such a dramatic change in 2 weeks and give him antibiotics and see what happened. I later showed the xray to Bill and he said you started TB tx right, uh - No. My thought was, he would followup in a week and if there was no change, I would start TB tx then. I ended up seeing him in 2 wks, and he said he was better. I believed him, but still planned on starting him on TB treatment based on his last xray. I got another CXR to see if there was a change, and was amazed at the change I saw. The R sided infiltrate, that had looked so much like TB to myself and others, was now almost gone. If you just saw this last xray you wouldn't jump to TB, but likely pneumonia. You usually don't see these dramatic changes in such a short period of time. So when you can't trust a history, sputum, or xray how does one make a diagnosis? Continued followup looking to see if the treatment I have chosen is working or not, and if not changing to something else is my current approach.