CBC report explained: haemoglobin, white cells and platelets in plain words

Medically reviewed by our consultant obstetrician & gynaecologist (MBBS, MS OBG). Last reviewed: 15 November 2026.

What is a CBC report?

The CBC, also called a haemogram, counts and measures the cells in a small sample of blood taken from a vein in the arm. Doctors ask for it in all kinds of situations, from a routine check to a fever or a planned operation. At Pai Hospital, the complete blood count is done in-house on automated analysers. For where it fits among the other tests, read about the blood count in our lab.

The report looks like a long list, but it falls into four groups. This page walks through them line by line, in plain words. It does not give normal values: the ranges are printed on your own report, beside each value, and they differ between laboratories and with age, sex and pregnancy.

Haemoglobin: what does it tell the doctor?

Haemoglobin (Hb) is the protein inside red cells that carries oxygen from the lungs to the rest of the body. It is usually the first line the doctor looks at.

• A low haemoglobin is called anaemia. In women it is common, for example with heavy or long periods, in pregnancy and while breastfeeding, or with a diet low in iron. Some long-standing illnesses and some inherited conditions can also lower it.
• A high haemoglobin is less common. It can be seen when the body is short of water, in people who smoke, and with some heart, lung or blood conditions.

The number alone does not tell the cause. That is why the doctor goes on to the red cell lines below.

Red cells and the indices: what do MCV, MCH and RDW mean?

These lines describe the red cells themselves. They are often called the red cell indices.

• RBC count. How many red cells there are in a set amount of blood.
• PCV or haematocrit (HCT). What share of the blood is made up of red cells.
• MCV. The average size of the red cells.
• MCH. The average amount of haemoglobin in each red cell.
• MCHC. How concentrated the haemoglobin is inside the red cells.
• RDW. How much the red cells vary in size from one another.

Read together, these help the doctor think about why haemoglobin may be low. Small, pale red cells point the doctor towards a shortage of iron, or towards an inherited trait such as thalassaemia trait. Large red cells point towards other causes, such as a low vitamin B12 or folate, some medicines, or thyroid or liver problems. These are only pointers. The doctor may add other tests, such as a ferritin test, which shows the body's iron stores, before deciding on a cause. This is one reason not to start iron tablets on your own: not every low haemoglobin is due to a shortage of iron.

White cells and the differential count: what do they show?

White cells (WBC) fight infection. The report gives the total white cell count (sometimes written TLC) and then the differential count, which splits the white cells into their types. Some reports show each type as a share of the total and also as an absolute count.

• Neutrophils. Often rise with bacterial infections, and also after surgery, with stress, with steroid medicines and in pregnancy.
• Lymphocytes. Often change with viral infections.
• Monocytes. Can rise during recovery from an infection and with some longer-lasting infections.
• Eosinophils. Often rise with allergies, asthma and worm infections.
• Basophils. A small group that rarely changes on its own.

A low white cell count can be seen in some viral fevers and with some medicines. In pregnancy and during labour, the white cell count is often higher than usual, and the doctor keeps that in mind. The pattern across the types tells the doctor more than the total count alone. Your doctor may ask for other blood tests alongside it; see CBC, CRP and infection blood tests.

Platelets: what does the count mean?

Platelets are tiny cells that help the blood to clot when a blood vessel is injured.

• A low platelet count can be seen in some viral fevers, with some medicines, in some conditions of pregnancy and in some blood disorders.
• A high platelet count can be seen after an infection or an operation, with a shortage of iron, and in some other conditions.

Some reports also show MPV, the average size of the platelets. Sometimes platelets stick together in the sample tube, and the analyser then counts fewer than there really are in the body. If a low count does not fit how you are, the doctor may ask for a repeat sample. During a fever, the platelet count is often repeated over the next days, because the trend tells the doctor more than one count.

Why is one flagged value read with symptoms and earlier reports?

Most reports mark a value outside the printed range with a flag, such as H for high, L for low or a star. A flag is a prompt for the doctor to look closer, not a diagnosis.

• A value slightly outside the range is common in healthy people, and a value inside the range does not always mean all is well.
• A recent infection, a heavy period, pregnancy, some medicines, or the body being short of water can all shift a value for a while.
• Earlier reports show whether a value is new, steady or changing. A value that has been the same for years means something different from one that has just changed.

So bring your earlier reports, old ones included, when you see the doctor. The doctor may repeat the count to see the trend before deciding anything.

Does a CBC need any preparation?

Very little. A normal meal before the test does not usually matter for a blood count, so it does not need fasting on its own. When it is drawn along with a test that does need fasting, the lab staff will tell you how to time the samples. Mention any medicines you take, since some of them can shift the counts. The steps before other common tests are covered under blood test preparation and reports.

How is the blood count done at Pai Hospital Laboratory?

The laboratory is on the ground floor, inside Pai Hospital, Vaddem, Vasco-da-Gama, Goa, and it is open 24 hours, every day. The complete blood count runs on automated analysers for routine tests. Every day, quality-control samples are run before patient reports are released; read what the lab checks every day.

Most routine reports are usually ready within hours. If your doctor adds a test that is sent to a partner laboratory, that report takes longer. Some tests run at set times; ask the lab when your report will be ready. See how long blood test reports take.

Who explains my CBC report?

Your treating doctor. The doctor reads the blood count together with your symptoms, your examination, your other results and your earlier reports. Please do not start or stop iron, antibiotics or any other medicine based on the report alone. If you feel unwell, see a doctor rather than waiting for a report. Written and reviewed by the Pai Hospital Team.

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This page is for general education and is not personal medical advice. Treatment depends on your own examination and reports, so please speak to a doctor about your situation. We do not carry out or offer sex determination of any kind.