Lab Differential

[medstudam]

I'm a bit uncertain of what exactly the Segs. and Bands mean in a lab diff. Also, in a viral condition, is it possible for the lymphocyte count to be elevated while the WBC count remains normal?

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[doc05]

how did you get to 3rd year without learning this stuff?

here's a start: seg=polys/PMNs/ neutrophils. look up the rest.

 

[scootad.]

oh lord

 

[medstudam]

Spare the criticism!

 

[Munchkin6245]

Segs and Bands are the way we differentiate neutrophils in the diff. Segs have a more segmented nucleus and a band is an unsegmented nucleus. Bands are normally reported if more than 10 are seen in a 100 cell differential.

The WBC count can be normal if the lymphocyte count is elevated.

 

[kc361]

I'm guessing the OP is asking what the *significance* of these items are in the differential, not necessarily their definition.

To the OP: Think about what a band cell is - an immature neutrophil. If the differential indicates increased WBC, with a high percentage of neutrophils (segs) and increased bands, this is referred to as a "left shift." It indicates that the bone marrow is working like the dickens to pump out new neutrophils in the setting of an acute infection. Increased bands usually carries a worse prognosis than an elevated WBC without bands.

 

[medstudam]

I'm guessing the OP is asking what the *significance* of these items are in the differential, not necessarily their definition.

To the OP: Think about what a band cell is - an immature neutrophil. If the differential indicates increased WBC, with a high percentage of neutrophils (segs) and increased bands, this is referred to as a "left shift." It indicates that the bone marrow is working like the dickens to pump out new neutrophils in the setting of an acute infection. Increased bands usually carries a worse prognosis than an elevated WBC without bands.

Thanks for the feedback!

THis is how I interpret the diff.
Increased Segs. by itself = inflammation
Increased Segs. + Bands = infection
Increased Bands by itself = infection (something killing off the segs.(mature) therefore only Bands left or could mean leukemia producing the band cell line.)

I have heard several different views on this from interns and residents which is the reason for the doubt!

Clinicals ROCK!!!!

 

[cubs3canes]

This makes me think of a funny story. During our first year we had to have small group sessions. Duirng one of the cases, there was a left shift. Some one in my group asked what a left shift was. The preceptor...she is a physician, a geriatrician responded " I think that is when all of the blood cells go to the left side of the arteries and veins."

When we left that class, we laughed for hours. Let me just say that we did not listen to anything she said in small groups for the rest of the year.

 

[scootad.]

Actually, while everyone seems to think they know what a left shift is, if you ask 3 people you will get 3 different answers! Its like gaydar, people know it when they see it but cant come to a consensus about what it is. Some think that the presence of bands alone (bandemia) is equivalent to a left shift. Others will say a higher than normal PMN % is equivalent to a left shift (with or without bands, with or without higher than normal white count). Still others will say a left shift is a higher than normal PMN % in the presence of a leukocytosis and a bandemia. I cant tell you how many times I've heard people use different definitions during my rotations.

whatever it is, it implies acute bacterial infection.

 

[omfsres]

Actually, while everyone seems to think they know what a left shift is, if you ask 3 people you will get 3 different answers! Its like gaydar, people know it when they see it but cant come to a consensus about what it is. Some think that the presence of bands alone (bandemia) is equivalent to a left shift. Others will say a higher than normal PMN % is equivalent to a left shift (with or without bands, with or without higher than normal white count). Still others will say a left shift is a higher than normal PMN % in the presence of a leukocytosis and a bandemia. I cant tell you how many times I've heard people use different definitions during my rotations.

whatever it is, it implies acute bacterial infection.

What about neutrophils >80%

 

[rxfudd]

Our immuno professor in 1st year was all too proud of the fact that he was one of the few people who actually know what the term left shift means. He says that historically, they used to use a counting device to record the differential on a CBC. The button that counted bands was the furthest button to the left, so when there was an acute infection/inflammation, you would be hitting that button much more frequently than usual because you had a bandemia (hence the term "left shift"). From that story, I would argue (and I've been told by most of my attendings) that a left shift is strictly an increase in immature cells (bands).

 

[cubs3canes]

Our immuno professor in 1st year was all too proud of the fact that he was one of the few people who actually know what the term left shift means. He says that historically, they used to use a counting device to record the differential on a CBC. The button that counted bands was the furthest button to the left, so when there was an acute infection/inflammation, you would be hitting that button much more frequently than usual because you had a bandemia (hence the term "left shift"). From that story, I would argue (and I've been told by most of my attendings) that a left shift is strictly an increase in immature cells (bands).

My histo profressor taught it like this: She turned the blood cell flow chart on its side, so that the hematopoietic stem cell was on the left and the mature RBC's and WBC's were on the right. Therefore, if you have a bandemia or lots of immature cells you are on the left side of the page. If you have lots of mature cells, you are on the right side of the page and that would be a right shift.

It would have been better if they used terms like down stream or up stream on the flow chart, but whatever. I agree it means acute bacterial infection, give antibiotics after BCx X 2 in two different places, if you suspect endocarditis, do it three times.

I am on Medicine Wards and you can tell.

 

[ramini]

I realize this may be elementary...

How does one calculate the band cell ratio? Isnt there a formula that you can used to determine whether or not a patient is under current infection? Also is it different in peds?

thanks

 

[edmadison]

Our immuno professor in 1st year was all too proud of the fact that he was one of the few people who actually know what the term left shift means. He says that historically, they used to use a counting device to record the differential on a CBC. The button that counted bands was the furthest button to the left, so when there was an acute infection/inflammation, you would be hitting that button much more frequently than usual because you had a bandemia (hence the term "left shift").

Wow, I thought everyone knew that!

Ed

 

[QuinnB]

it technically can include things earlier than bands, although the significance of a blastemia left shift is completely different (AML) compared to a bandemia left shift (acute bacterial infection).

Our profs told us that they used to write cell lineage differentiation from left to write (like we read) with the hematopoeitic cells on the far left and the PMN, eos, baso, etc...on the far right. The counters were then designed with this "convention" in mind, although they only counted as far left as bands as opposed to the hematopoetic cells.

 

[DOtobe]

Our immuno professor in 1st year was all too proud of the fact that he was one of the few people who actually know what the term left shift means. He says that historically, they used to use a counting device to record the differential on a CBC. The button that counted bands was the furthest button to the left, so when there was an acute infection/inflammation, you would be hitting that button much more frequently than usual because you had a bandemia (hence the term "left shift"). From that story, I would argue (and I've been told by most of my attendings) that a left shift is strictly an increase in immature cells (bands).

I never knew this until the attending on my last rotation (ID) told me this. I guess he's one of the few too, lol.

 

[Slothbear]

yo -- don't get sucked into thinking inc bands = acute bacterial infection necessarily. It means there is acute inflammation -- one cause can be bacterial infection. You see inc bands with acute pancreatitis.

 

[lapelirroja]

doing a 100 cell diff (or 200) is still performed on a button counter...it's not really 'historical.' if automated methods produce strange data or if the machine is not sure what it is seeing, a manual diff is performed as a reflex test.

--med tech