CBC Blood Test: What It Shows and How to Read Your Report

What a CBC measures

A complete blood count looks at the three main types of cells in your blood: red cells, white cells and platelets. It takes one small blood sample from the arm, and results are usually ready the same day.

• Red blood cells carry oxygen around the body. The report shows haemoglobin (Hb), the red cell count, and the size and colour of the cells.
• White blood cells fight infection. The report shows the total count and the different types (the "differential").
• Platelets help the blood to clot and stop bleeding.

When a doctor asks for a CBC

• Fever, to look for signs of infection, and to follow suspected dengue or typhoid (see the fever guide)
• Weakness, tiredness, dizziness or pale skin, to check for anemia
• Pregnancy, where anemia is common and needs treatment
• Heavy periods, which can lower haemoglobin over time
• Before surgery or procedures
• Routine check-ups, and to monitor long-term conditions or certain medicines

Understanding your CBC report

Every laboratory prints its own normal range next to each result, and ranges differ slightly between labs, by age, and between men and women. The ranges below are typical adult values, for general understanding only. Always compare with the range on your own report, and let a doctor interpret the whole picture.

What common results usually mean

Low haemoglobin (anemia)

Anemia is very common in Pakistan, especially in women and children. It can cause tiredness, breathlessness, dizziness, hair fall and pale skin. The red cell size helps point to the cause:

• Small red cells (low MCV and MCH): most often iron deficiency. Thalassemia trait, which is common in Pakistan, can look similar, so the doctor may ask for iron studies or an Hb electrophoresis test before starting iron.
• Large red cells (high MCV): can be due to low vitamin B12 or folate, some medicines, or liver and thyroid problems.
• Normal-sized cells: can be seen with long-term illness, kidney disease, recent blood loss, or early iron deficiency.

High white cell count

Usually a sign that the body is fighting an infection, most often bacterial, or inflammation. Stress, steroids and pregnancy can also raise it slightly. Very high or abnormal counts need further checks.

Low white cell count

Can happen in viral infections, including dengue, and in typhoid. Some medicines and other conditions can also lower it. A doctor decides whether it needs a repeat test or more investigation.

Low platelets

In Karachi, low platelets during a fever often raise the question of dengue. Platelets can also fall in other viral infections, malaria and some other conditions. In suspected dengue, doctors usually repeat the CBC daily or every other day, because the trend of the platelets and haematocrit matters more than a single result.

High platelets

Often temporary after an infection or with iron deficiency. Persistently high counts need a doctor's review.

How to prepare for a CBC

• No fasting is needed for a CBC alone. If other tests like sugar or cholesterol are being done at the same time, you may be asked to fast.
• Drink water as normal.
• Tell the lab and your doctor about medicines you take, recent illness, and whether you are pregnant.
• For dengue monitoring, try to repeat the test at the same lab so the results are easier to compare.

Where to get a CBC in Karachi, and the cost

A CBC is available at almost every major diagnostic laboratory and hospital lab in Karachi, and many labs also collect samples from home. Prices vary between labs and change over time, so check the current price with the lab before you go. A CBC is one of the cheaper blood tests, and results usually come the same day.

How Hiba Care Clinic can help

Many patients get a CBC done but are not sure what the numbers mean. Dr. Fanila Adhi can go through your report at the clinic, or you can send photos of it in an online consultation over WhatsApp. She will explain the results in plain words, tell you whether anything needs treatment, and suggest further tests only if they are really needed.

For fever, weakness, or anemia in women, you can also read about seeing a general physician or a lady doctor at the clinic, and about vitamin D deficiency, which often causes similar tiredness and aches.

Common questions