MCHC (Mean Corpuscular Hemoglobin Concentration)

MCHC stands for mean corpuscular haemoglobin concentration: the average concentration of haemoglobin inside your red blood cells. It is not a separate measurement but a calculation from your haemoglobin and your haematocrit.

Where MCH shows how much haemoglobin a cell contains, MCHC shows how densely that haemoglobin is packed. A cell can be large and still hold a normal concentration.

The value is always assessed together with your MCV and MCH. Of the three red cell indices, MCHC varies least, which is exactly why a deviation stands out.

MCHC completes the picture your MCV and MCH give. A low MCHC means your red blood cells are paler than normal, which fits longer-standing iron deficiency or thalassaemia.

A high MCHC is unusual, because a red blood cell can only hold so much haemoglobin. When the value is raised anyway, it can point to hereditary spherocytosis, a condition in which red blood cells are sphere-shaped.

A raised MCHC can also have a technical cause, for instance when the blood sample is damaged or very high in fat. The laboratory and your doctor always weigh that possibility before drawing conclusions.

MCHC is included automatically in a full blood count. That is done for complaints such as fatigue, pallor or breathlessness, during a general health check, and when monitoring anaemia.

The value is most useful alongside your MCV and MCH: together they point towards the cause of an abnormal haemoglobin.

You do not need to fast for it. The value comes from the same tube of blood as the rest of your blood count.