Mean Corpuscular Hemoglobin Concentration - Complications With Cold Agglutinin

Complications With Cold Agglutinin

Because of the way automated analysers count blood cells, a very high MCHC (greater than about 370 g/L) may indicate the blood is from someone with a cold agglutinin. This means that when their blood gets colder than 37°C it starts to clump together. As a result, the analyzer may incorrectly report a low number of very dense red blood cells for blood samples in which agglutination has occurred.

This problem is usually picked up by the laboratory before the result is reported. The blood is warmed until the cells separate from each other, and quickly put through the machine while still warm.This is the most sensitive test for iron deficiency anemia.

There are 4 steps to perform when an increase MCHC(>370 g/L or 37.0 g/dL) is received from the analyzer:

• 1. Remix the EDTA tube - if the MCHC corrects, report corrected results
• 2. Incubation at 37°C - if the MCHC corrects, report corrected results and comment on possible cold agglutinin
• 3. Saline replacement - Replace plasma with same amount of Saline to exclude interference e.g. Lipemia and Auto-immune antibodies - if the MCHC corrects, report corrected results and comment on Lipemia
• 4. Check the slide for Spherocytosis (e.g. in Hereditary spherocytosis, among other causes)