Ok, I'm ******ed

[DancingFajitas]

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So...I'm a little bit confused. I'm wondering how you can tell that the cause of an elevated WBC count is something more serious than just a local infection? For example, someone who comes in with UTI will have an elevated white count but someone with urosepsis will as well? I understand that you need to take into account hx, physical and vitals, but by just looking at the white count, how can you tell how serious the infection is? So how can you tell just by WBC count when you need some more serious labs than a UTI, and something like a blood culture? I'm also wondering if small infections such as mono or skin infections cause much of an inc in WBC and if so will there be a leukocytosis or inc neutrophils corresponding to a viral or bacterial infection respectively?

 

[Rendar5]

So...I'm a little bit confused. I'm wondering how you can tell that the cause of an elevated WBC count is something more serious than just a local infection? For example, someone who comes in with UTI will have an elevated white count but someone with urosepsis will as well? I understand that you need to take into account hx, physical and vitals, but by just looking at the white count, how can you tell how serious the infection is? So how can you tell just by WBC count when you need some more serious labs than a UTI, and something like a blood culture? I'm also wondering if small infections such as mono or skin infections cause much of an inc in WBC and if so will there be a leukocytosis or inc neutrophils corresponding to a viral or bacterial infection respectively?

The honest to god truth that current research shows is that an initial WBC is not gonna tell you anything important about a patient unless it's extremely high or extremely low. And I don't mean simply "abnormal". We still use it all the time to convince ourselves someone's sick for who knows what reason, maybe it's just our instinct. Even I look at it and consider ordering it when I know it's not gonna tell me a whole lot.

What it is useful for, though, is looking for a trend (for recovery), putting someone on course for a sepsis workup/treatment plan if they're only displaying one other SIRS criteria, and for looking at the differential. Someone with a WBC of 8.0, but with a bandemia is someone who has a bacterial infection. Someone with 5% neutrophils is neutropenic. And yes, you will note a change from the normal distribution when someone has a bad cellulitis or has mono. And yes, you will meet surgeons who tell you that the WBC is an important number in determining if someone has appendicitis (they're wrong, but don't bother trying to convince them they're wrong).

So the overall point is for initial diagnosis: don't look at the WBC in most patients, look at the differential, except in the case that you clinically suspect someone is septic and they don't fit into the SIRS critera without a WBC

 

[Scaredshizzles]

So...I'm a little bit confused. I'm wondering how you can tell that the cause of an elevated WBC count is something more serious than just a local infection? For example, someone who comes in with UTI will have an elevated white count but someone with urosepsis will as well? I understand that you need to take into account hx, physical and vitals, but by just looking at the white count, how can you tell how serious the infection is? So how can you tell just by WBC count when you need some more serious labs than a UTI, and something like a blood culture? I'm also wondering if small infections such as mono or skin infections cause much of an inc in WBC and if so will there be a leukocytosis or inc neutrophils corresponding to a viral or bacterial infection respectively?

There is no cut off, it depends on the patient...A very septic patient might also have a very low WBC...(Many infections can temporarily suppress the BM). But most patients who have relatively normal WBC#s at baselines (5 or so), won't get a WBC # over 15k from a local infection....There are plenty of exceptions I'm sure, but a WBC# over 15k (especially with a strong left shift) is an extra red flag for a very serious infection that has entered the blood stream...(But certainly a patient can be septic with a WBC# of 12k or a WBC# of 1k too.)

 

[45408]

The difference between a UTI and urosepsis would hopefully be more than just a difference in the WBC count. You have to look at the whole clinical picture. Does the patient have altered mental status or hemodynamic abnormalities?

 

[gluon999]

how can you tell how serious the infection is?

Look at the patient. What is the temp? Is it 101 or is it 104...there is a significant difference. What is the heart rate...does it go up appropriately when they sit up? What is their BP like and equally importantly, what is their baseline resting BP? Do they get orthostatic or dizzy when they sit up? Can they ambulate as usual? Are they mentating well? Is their WBC high? If yes, is it 12k or 22k? What did the blood cx show? Are they showing signs of end organ dysfunction like ARF, CHF, AMS, etc.

Think about these questions and their answers as you evaluate and workup the patient. With experience you will be able to tell whether a patient has just another UTI or is truly septic.

 

[The Angriest Bird]

Unless the WBC is above 20,000, it alone is not sensitive or specific for pretty much anything