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Old 09-24-2017, 04:52 PM
Wesley Clark Wesley Clark is online now
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How do medical professionals differentiate between an infection and an autoimmune disorder

Just watched a movie where someone supposedly had a massive internal infection and was being treated for the infection and not getting better, but it turned out it was an autoimmune disease. Once they treated for that the person got better.

In situations like that how do medical professionals distinguish whether what is happening is an infection or autoimmune disorder? Is there a lab test that will distinguish the two?
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Old 09-24-2017, 05:07 PM
Hari Seldon Hari Seldon is offline
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IANAD, but I read the medical mystery that appears about every second week in the NY Times Sunday magazine. Basically, they consider the symptoms and, if they suspect an infection, they will try to culture it. Often they will try to treat the infection with antibiotics while waiting for the lab results. If they find no infection, they will often find a specialist who is familiar with the set of symptoms and s/he will carry out further tests. These days, there are also expert systems that can make suggestions.

But Times prints only stories of successful diagnoses and I wonder how many cases are never correctly diagnosed. At any rate, what I have said must be taken with a large grain of salt.
Old 09-24-2017, 07:25 PM
Jackmannii Jackmannii is offline
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Originally Posted by Hari Seldon View Post
At any rate, what I have said must be taken with a large grain of salt.
There's a test for that (serum sodium level).

What movie featured such a diagnostic dilemma?

Last edited by Jackmannii; 09-24-2017 at 07:26 PM.
Old 09-24-2017, 07:48 PM
dstarfire dstarfire is offline
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The immune system has several types of cells, that specialize in different things. One of these basically has the job of targeting: it grabs on to invaders then sets off a local alarm. Part of the bodies response is producing many more targeting cells that are keyed to this specific invader (maybe because it's biologically cheaper or to reduce collateral damage, I don't know/recall). a blood sample will get you some of these focused targeting cells, and a bit of analysis will tell you what they're targeting.

This is based on vague recollection of something I read in popular media (i.e. not especially trustworthy) so it's almost certainly mostly wrong.
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Old 09-24-2017, 10:10 PM
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Beckdawrek Beckdawrek is online now
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Isn't a white blood cell count helpful In determining if someone has an infection. Also there is the spinal tap thing they do.
Old 09-25-2017, 08:13 AM
Qadgop the Mercotan Qadgop the Mercotan is offline
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It can be tough to tell. Infections are much more common than autoimmune diseases, so they're the first thing we think of in low risk patients. We look at white blood counts, symptoms and signs, and really rely on cultures to find an infection. When it doesn't respond to treatment the way we expect an infection to, then we start thinking 'autoimmune'.

Real challenges occur in patients with known autoimmune disease who have sudden symptoms; are they having a disease flare or an infection? They are more prone to both.

More sophisticated tests are being brought to bear on answering these questions, but it is an area of medicine that is still far more art than science.
Old 09-25-2017, 08:46 AM
chrisk chrisk is offline
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I would think it's more a case of when to look for A+B versus just A... the autoimmune disease makes it more difficult or impossible to fight off an infection, but the infection is still there, right?
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