MCHC blood test: normal range and what the result means

MCHC (mean corpuscular haemoglobin concentration) is one of the red blood cell (erythrocyte) indices, and it shows how densely haemoglobin is packed inside each erythrocyte. It is calculated from the haemoglobin and haematocrit values and is most often assessed together with MCV (the mean corpuscular volume) and MCH (the mean amount of haemoglobin in a red blood cell). All three belong to the group of red blood cell indices, which is performed automatically together with the complete blood count (CBC). According to MedlinePlus, these indices help the doctor distinguish between different types of anaemia by the size and shape of the red blood cells and the amount of haemoglobin in them. MCHC on its own is rarely used for a diagnosis — it is always assessed together with haemoglobin, haematocrit, the red blood cell count, MCV and MCH, and in the light of the overall clinical picture.

• When a complete blood count (CBC) is done and the red blood cell indices are assessed — most often as part of a standard preventive check
• When you feel tired, weak, pale or short of breath — when anaemia is suspected
• When the complete blood count has found a changed haemoglobin, haematocrit or red blood cell count and the type of anaemia needs to be established
• When there are known inherited blood disorders in the family, for example thalassaemia or hereditary spherocytosis
• When following the course of treatment for anaemia or another blood disorder

How to prepare

• No special preparation is needed for a test of the red blood cell indices (MCHC included)
• The test is done together with the complete blood count, taking a blood sample from a vein

Reference range

According to the MedlinePlus complete blood count article, the MCHC range is 32-36 g/dl, that is 320-360 g/l. The exact interval depends on the laboratory and is given on your own result sheet, most often in g/l units, so if any questions come up it is worth discussing them with your doctor.

A raised MCHC

A raised MCHC means that haemoglobin is packed more densely in the red blood cells than usual. According to MedlinePlus, the possible causes are haemolytic anaemia (when the red blood cells break down too early) and hereditary spherocytosis, a rare genetic disorder in which the red blood cells are round, spherical in shape rather than the usual flat disc shape. The exact cause is established by a doctor, having assessed it together with the other blood test results.

• Haemolytic anaemia — a condition in which the red blood cells break down faster than the body can produce them
• Hereditary spherocytosis — a genetic condition in which the red blood cells are round, spherical in shape rather than the usual flat disc shape

What to discuss with a doctor when MCHC is raised

• The other red blood cell indicators — MCV, MCH, haemoglobin, haematocrit and the red blood cell count in the overall picture
• Family history for inherited blood disorders
• Whether there are other signs of haemolysis, which the doctor assesses with additional tests
• When to repeat the test, so that the change over time can be seen

A low MCHC

A low MCHC means that less haemoglobin is packed into the red blood cells than usual — the cells look paler. According to MedlinePlus, this is typical of iron deficiency anaemia and of thalassaemia, an inherited blood disorder that disrupts haemoglobin production. Iron markers and the other red blood cell indices help to tell the cause apart.

Possible causes of a low MCHC

• Iron deficiency anaemia — a condition that happens when there is not enough iron in the body
• Thalassaemia — an inherited condition that disrupts normal haemoglobin production

What to discuss with a doctor when MCHC is low

• Iron markers — ferritin, iron, transferrin saturation — to confirm or rule out iron deficiency
• The other red blood cell indicators — MCV, MCH, haemoglobin and haematocrit in the overall picture
• Family history for thalassaemia or other inherited blood disorders
• Diet and possible causes of blood loss