The Complete Blood Count (CBC) is the workhorse of lab testing — it is ordered for everything from routine check-ups to investigating fatigue, fever or suspected infection. It measures the three main families of cells in your blood.
Red blood cells (RBC) and haemoglobin carry oxygen. Low levels mean anaemia — the cause could be iron deficiency, B12 deficiency, blood loss or chronic disease, and the treatment depends entirely on the cause. High levels are less common and need investigation.
White blood cells (WBC) are your immune army. A high count often signals infection or inflammation; a very high or very low count, or unusual cell patterns, needs a doctor's review. Platelets help blood clot — too few raise bleeding risk, too many raise clotting risk.
The CBC alone rarely gives a final answer; it points in a direction. Share your results with a doctor, who will combine them with your history and further tests. What makes a CBC valuable is not the number of values — it is the pattern they form together.
What is a CBC blood test?
A Complete Blood Count (CBC) is a blood test that measures the three main families of cells in your blood — red cells, white cells and platelets — and is used for check-ups and investigating fatigue, fever or infection.
What do abnormal CBC results mean?
Low haemoglobin suggests anaemia, a high white cell count often signals infection or inflammation, and abnormal platelets raise bleeding or clotting concerns — each needs a doctor’s interpretation.
How do you prepare for a CBC and interpret it sensibly?
Preparation is simple: a CBC usually needs no fasting, but confirm with the lab because doctors often combine it with glucose or lipid tests that do require 8–12 hours of fasting. Tell the lab about any medicines, because some affect blood counts. When the report arrives, don’t panic over single flags — read it in groups. Haemoglobin and red cell indices tell you about anaemia: low haemoglobin with small cells usually points to iron deficiency, while large cells suggest B12 or folate deficiency, and your doctor will choose the right next test. White cell count and its differential signal infection or inflammation, and sometimes allergies — a high count alone doesn’t name the cause. Platelets reflect clotting risk: very low counts need attention, very high counts need investigation. The CBC is a direction-finder, not a verdict: it tells your doctor where to look next, and the pattern across values matters more than any one number. Share the report with your doctor for interpretation.
