MCHC blood test: normal range explained

MCHC measures how concentrated the haemoglobin is inside your red blood cells: the amount of haemoglobin relative to the size of the cell, in g/dL. Testing.com describes it as how much of the space inside each red cell is made of haemoglobin.

It is the third of the red cell indices on a CBC, with MCV (size) and MCH (haemoglobin per cell). A low MCHC means the cells are paler than usual (hypochromic); a high MCHC, Testing.com says, may be seen with spherocytosis, a rare inherited condition, or when red cells clump together.

Doctors read MCHC with the other indices to help find the cause of anaemia. Testing.com says the indices are checked when someone has signs of anaemia, listing tiredness, headaches and numbness or tingling early on, and shortness of breath and pale skin as it progresses.

Because MCHC is part of every CBC, it also appears at routine check-ups and whenever a CBC is ordered to monitor a condition or treatment. MedlinePlus lists infections, anaemia, immune disorders and blood cancers among the reasons a CBC is repeated.

MCHC moves with whatever changes the haemoglobin in your red cells, and a few things can distort the measurement itself.

• Iron deficiency lowers MCHC, because the cells carry less haemoglobin for their size.
• Hereditary spherocytosis, a rare inherited condition, can raise it, and red cells clumping together (agglutination) can make it read high.
• Thalassaemia and lead poisoning are listed causes of small red cells (a low MCV), which is read beside MCHC.
• Dehydration, diet, activity level, medicines and a menstrual period can affect CBC results.
• Each lab sets its range from its own equipment, so the printed limits differ slightly between reports.