O Troubleshooting

What Kinds of Clinical Situations Come to Mind When the MCHC Is Above 36.0%?

A 72-year-old man was seen in the emergency department for gastrointestinal bleeding and sepsis, and was subsequently admitted. He had the usual emergency department tests ordered: chemistry panel, PT/aPTT, urinalysis, and CBC. His CBC showed:

RBC 3.58 X 1012/L

MCV 85.3 fL

MCH 29.8 pg

MCHC 34.9%

PLT 16 X 109/L

During his 3-day stay, the patient's red cell indices began to fluctuate (MCH and MCHC) and his hemoglobin results showed variability. The CBC results on day 3 were:

WBC 15.9 X109/L

RBC 2.80 X 1012/L

MCV 85.5 fL

MCH 33.4 pg

PLT 79 X 109/L

Several indices in the CBC were flagged (asterisks) and warranted further investigation. At first, when the technologists noticed these increases, several scenarios came to mind: 1) cold agglutinins, 2) lipemia, or 3) spherocytes. The technologist followed standard operating procedures (SOP) for an elevated MCHC. First, the sample was warmed in a 37°C water bath for 30 minutes and then reanalyzed on the Coulter LH750. The results remained unchanged. At times, cold agglutinins require longer incubation in a water bath to correct. This was not the case with this particular specimen, since it was incubated for 30 minutes longer. The MCHC refused to budge even after longer incubation. When a sample is incubated for 30 minutes or longer, cells settle away from the plasma and the technologist can observe the plasma for the presence of lipemia. The observations revealed a slight increase (or cloudiness), but not true lipemia, which interferes with the MCHC. The final step was to look for spherocytes on the peripheral smear. The smear was negative for spherocytes. At this point the technologist could not account or explain the MCHC, and reported the results commenting under the MCHC: no hemolysis, no presence of cold agglutinins, and no spherocytes.

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