Jump to content
Sign in to follow this  
Bubbles

High MCHC

Recommended Posts

Just gathering inputs on what to do when you have MCHC >37  after dilution and prewarming of the slightly lipemic sample. 

Thank you.

Share this post


Link to post
Share on other sites


On 7/19/2018 at 9:26 AM, Bubbles said:

Just gathering inputs on what to do when you have MCHC >37  after dilution and prewarming of the slightly lipemic sample. 

Thank you.

What is the diagnostics? Is there any indication of hemolytic anemia or abnormality in manual differential (if performed)? 

Share this post


Link to post
Share on other sites
On 7/19/2018 at 12:26 PM, Bubbles said:

Just gathering inputs on what to do when you have MCHC >37  after dilution and prewarming of the slightly lipemic sample. 

Thank you.

For interference with the hemoglobinometer due to lipemia, we would do a saline replacement. 

If due to strong cold agglutinins, we would warm for 10 minutes or so.  For really really string cold agglutinins that cannot be resolved, we would blank out those parameters that are affected.

Scott

Share this post


Link to post
Share on other sites

If you feel the high MCHC is due to the lipemia, a 1:3 or 1:5 dilution may help.  If not, plasma replacement or "wash" procedure should work.  If the MCHC is still elevated, think about other reasons for this--cold agglutinin, abnormal hemoglobin, dehydration?  Also, look at the other RBC indices: if the MCV & MCH are abnormal, I wouldn't expect the MCHC to be normal.

In the case of a severe cold agglutinin, a 1:5 dilution with pre-warmed diluent may be helpful.

Share this post


Link to post
Share on other sites

Just one more note.  While the MCH represents the total Hgb in RBCs, the MCHC reflects the concentration of Hgb in the RBCs.   So for hypochromic RBC patients, the MCHC will be low.  But it is physically impossible to have a concentration much above 37 for the MCHC.  That is why anything higher than that must be resolved.

Scott

Share this post


Link to post
Share on other sites
Posted (edited)
On ‎7‎/‎26‎/‎2018 at 12:15 PM, SMILLER said:

Just one more note.  While the MCH represents the total Hgb in RBCs, the MCHC reflects the concentration of Hgb in the RBCs.   So for hypochromic RBC patients, the MCHC will be low.  But it is physically impossible to have a concentration much above 37 for the MCHC.  That is why anything higher than that must be resolved.

Scott

Scott, I have always understood the MCHC as being the statistical Mean Hgb concentration of the rbc  whose volume would be in the middle the lowest and highest volumes of a group of packed rbc's representing the HCT. The calculation for the MCHC is Hgb/HCTx 100= MCHC. Also, we practice to incubated for 30min or an hour depending on how strong the cold agglutinin is as represented by the elevated MCHC >36.0. If lipemia is found then we would do a saline replacement. And if there is a combination of lipemia and cold agglutinin we would replace with warm saline. Additionally, I understand the MCH as being the concentration of Hgb of the rbc that is present in the group of counted rbc's and whose volume is midway between the lowest and highest volumes of this group. The equation is Hgb/RBC's Counted x a given constant (where the given constant will act to manipulate the decimal place such that the result is given to one decimal place) = MCH. So with the MCHC one can see how rbc morphology will effect the Mean Hgb concentration determined by the MCH. In other words, the instrument that is used to count the red cells and determine the volume can not know the shape of these red cells. The hematocrit can give an indication of the shape of the red cells by the way they pack. A group of normal shaped red cells will pack differently as compared to acanthocytic red cells. This is why the result obtained for the MCH is often different then the result obtained for the MCHC. Another anomaly that can occur with an increased MCHC is an H&H check fail whereby the HGB is not 3x +/- 3 the HCT. This failure can occur with low MCV, rbc agglutination, lipemia, excessive icterus and/ or hemolysis, or the age of the specimen, to name a few. However the low MCV may often not be accompanied by an elevated MCHC. 

Edited by rravkin@aol.com

Share this post


Link to post
Share on other sites

OK. But I would say that results for MCH and MCHC are different because they are measuring two different things.  And I am not so sure that using the "rule of three" or "H&H check fail" to check results is very useful when we can just look to the indices for troubleshooting.  For example:

I see the MCH as the Mean Cell Hemoglobin, that is: the total amount of hemoglobin in the cell (NOT the concentration of Hgb).  So for high MCVs, the MCH will tend to be high, and for low MCVs, the MCH will tend to be low.

The MCHC, on the other hand, is the Mean Cell Hemoglobin Concentration.   Cell size, by itself, does not matter here.  However, consider an iron-deficiency anemia where not only are the cells small (low MCV and MCH) but the concentration of Hgb is also low,  which will result in a low MCHC.

However, the concentration of Hgb can only be so high (no more than 36 or 37), as it is physically impossible to have a higher density of Hgb beyond that.  (Again, the MCV  or MHC is not the issue here.)  This is why when one has a very high MCHC you have to try to resolve it.  Too much lipemia skews hemoglobinometer results upward, resulting in a higher Hgb and no change to the RBC or MCV.  Cold agglutinins skew the RBC count downward, with no change in Hgb.  In either case, if you do the calculations for MCHC, you get a impossibly high result.

Scott

 

Share this post


Link to post
Share on other sites
Posted (edited)
On ‎8‎/‎3‎/‎2018 at 10:31 AM, SMILLER said:

OK. But I would say that results for MCH and MCHC are different because they are measuring two different things.  And I am not so sure that using the "rule of three" or "H&H check fail" to check results is very useful when we can just look to the indices for troubleshooting.  For example:

I see the MCH as the Mean Cell Hemoglobin, that is: the total amount of hemoglobin in the cell (NOT the concentration of Hgb).  So for high MCVs, the MCH will tend to be high, and for low MCVs, the MCH will tend to be low.

The MCHC, on the other hand, is the Mean Cell Hemoglobin Concentration.   Cell size, by itself, does not matter here.  However, consider an iron-deficiency anemia where not only are the cells small (low MCV and MCH) but the concentration of Hgb is also low,  which will result in a low MCHC.

However, the concentration of Hgb can only be so high (no more than 36 or 37), as it is physically impossible to have a higher density of Hgb beyond that.  (Again, the MCV  or MHC is not the issue here.)  This is why when one has a very high MCHC you have to try to resolve it.  Too much lipemia skews hemoglobinometer results upward, resulting in a higher Hgb and no change to the RBC or MCV.  Cold agglutinins skew the RBC count downward, with no change in Hgb.  In either case, if you do the calculations for MCHC, you get a impossibly high result.

Scott

 

Thank you for the information Scott. It did compel some research where I found that the MCH actually measures the mass of hgb of the rbc in the middle (based on volume) of a group of counted rbc's while the MCHC is measuring the average hgb concentration of a group of packed rbc's, and therefore I stand corrected. I guess that I suspected a relationship between the MCH and MCHC because they both use the measured Hgb as numerators in their respective equations.

Our DXH will flag an H&H check fail which will trigger a closer look at the H&H and the indices. If your MCV is low, MCH normal, and MCHC is normal to low, your H&H check fail is more than likely do to an rbc microcytosis. Here the cause of the H&H check fail is a higher HCT do to the microcytic rbc's. If you have an H&H check fail and the MCV and MCH are normal, but MCHC is >36 and your Hgb compares to the HCT as being higher you are probably looking lipemia; also you whole blood sample may appear a brighter than usual red color; but cold agglutin can cause these same results with darker red sample color. However, if your have an H&H check fail with low to normal MCV, low MCH, and normal to low MCHC you may be looking at an aged specimen. I have experienced these scenarios as I am sure you have, as well as many who attend this site but the last scenario that I described is not something I seen in the hospital setting very often but in a reference lab setting it is rare. Thank you again Scott and thank you PathLab Talk for the opportunity to conversate.

Edited by rravkin@aol.com

Share this post


Link to post
Share on other sites

The problem we have here from time to time, is that we will have something like an obvious iron-deficiency anemia where the MCV, MCH, MCHC are all low, as you would expect.  But when certain techs (who should know better) see that H&H check fail flag, they immediately incubate the specimen at 37, thinking this will correct "something".  It is a waste of time, of course.  So that with many pathological conditions, the H&H "rule of three" is supposed to fail, and further manipulation to "correct" the H&H fail flag is not indicated.

Scott

Share this post


Link to post
Share on other sites
8 hours ago, SMILLER said:

The problem we have here from time to time, is that we will have something like an obvious iron-deficiency anemia where the MCV, MCH, MCHC are all low, as you would expect.  But when certain techs (who should know better) see that H&H check fail flag, they immediately incubate the specimen at 37, thinking this will correct "something".  It is a waste of time, of course.  So that with many pathological conditions, the H&H "rule of three" is supposed to fail, and further manipulation to "correct" the H&H fail flag is not indicated.

Scott

Have you ever tried using this scenario in an in-lab continuing education exercise? 

Share this post


Link to post
Share on other sites
19 hours ago, rravkin@aol.com said:

Have you ever tried using this scenario in an in-lab continuing education exercise? 

Not a bad idea!  There are a few other things that could be gone over as well, like why one has to do a smear review when you have a high neutrophil or RDW.

I believe our Hema manager actually included questions like this on our last annual competency.  They try to ask about stuff that associates are slipping on.

Scott

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

  • Advertisement

×

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.