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.