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Understanding your complete blood count results

Te mārama ki ō hua whakamātaunga kaute toto

Blood is about 55% plasma, 4% white blood cells and platelets, and 41% red blood cells.Your blood is made up of red blood cells, white blood cells, platelets and plasma. Checking your blood count, often called a complete blood count (CBC) or full blood count (FBC), looks at each of the different parts of your blood.

Terms used in the complete blood count results

Haemoglobin: this is found in your red blood cells. It carries the oxygen around your body.

Haematocrit: this is the proportion of your blood made up of red blood cells.

MCV: this stands for mean cell volume. It measures the size of your red blood cells.

MCH: this stands for mean cell haematocrit. It is the average amount of haemoglobin in each red blood cell.

Platelets: these form the part of your blood that helps to make clots if you cut yourself or are injured.

Neutrophils, lymphocytes, monocytes, eosinophils and basophils: these are all types of white blood cells. They form part of your immune system, and each fights off different kinds of infections.

WBC: this stands for white blood cells. It's the total number of white blood cells in your blood, adding together all the different types of white blood cells.

Normal results

If you have a copy of your test results, it will show your results and a normal range for each test. The normal ranges may vary depending on your gender and age group and whether you're pregnant or have any underlying health conditions. So, the normal ranges shown on your test results may not be exactly right for you. Discuss your results with your general practice team if you're unsure.

High results

There can be several reasons for your red blood cells being too high, including dehydration and smoking. You may need to have more tests to find the cause.

If your white blood cells are too high, your body is probably fighting an infection. You might need to get this checked again later to make sure your levels have returned to normal.

Platelet numbers can be high for several reasons. It can mean you're fighting an infection. Platelet numbers also rise after surgery. A rare cause is essential thrombocythaemia.

Low results

If your haemoglobin is too low, it means you have anaemia. There are several possible causes for this, such as low iron levels, low vitamin levels and bleeding. You may need more tests to find out what is causing your anaemia.

If your white blood cells are too low, it may mean you have an infection, or your immune system might not be working properly. You may need more blood tests to find out why and you may need a bone marrow biopsy.

If your platelets are too low (called thrombocytopenia), this can make you bruise or bleed more easily. There are lots of reasons why this might happen. For example, after an infection or because of medicines you're taking. You may need to have another blood test if your level is very low.

If you have any questions about your complete blood count, talk to your general practice team.

Written by HealthInfo clinical advisers. Last reviewed October 2022.


See also:

What blood is made of

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