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The Full Blood Count, or FBC, is the single most-ordered blood test in the UK. If you’ve had any blood test on the NHS or privately in the last five years, there’s a good chance an FBC was part of it. This guide explains what it measures, what the numbers mean, and when it’s worth booking one privately.
A Full Blood Count (called Complete Blood Count, or CBC, in the US) measures the concentration and characteristics of the three main cell types in your blood: red blood cells, white blood cells, and platelets. A single sample from your arm is analysed by an automated haematology analyser at a laboratory, and the result usually includes 15 to 25 individual values.
Red blood cells carry oxygen from your lungs to the rest of the body. The FBC reports:
A low Hb is anaemia. The other red cell indices help tell what type of anaemia it is, which is important because iron-deficiency anaemia, B12-deficiency anaemia, and other anaemias have different causes and treatments. An Anaemia Blood Test can help pin down the type and cause.
White blood cells are your immune system. The FBC reports:
A high WBC often means a recent or current infection. A low WBC can occur after viral infections, with some medications, or with bone marrow problems.
Platelets are small cell fragments that make blood clot. The FBC reports:
Very low platelets can raise bleeding risk. Very high platelets can raise clotting risk. Both extremes need a GP conversation.
An FBC is ordered by clinicians in almost every situation where a blood test is warranted. Common private testing reasons include:
Reference ranges vary slightly by laboratory. Approximate UK adult ranges for orientation:
| Marker | Typical adult range | Units |
|---|---|---|
| Haemoglobin (women) | 120–150 | g/L |
| Haemoglobin (men) | 130–170 | g/L |
| White cell count | 4.0–11.0 | ×10⁹/L |
| Platelets | 150–400 | ×10⁹/L |
| MCV | 80–100 | fL |
| Neutrophils | 2.0–7.5 | ×10⁹/L |
| Lymphocytes | 1.0–4.0 | ×10⁹/L |
Always use the range printed on your own report, not this table.
| Pattern | What it suggests |
|---|---|
| Low Hb + low MCV | Iron deficiency anaemia. Very common in menstruating women and often responds to dietary iron and, when needed, supplementation. Investigate the cause: heavy periods, gut blood loss, or poor absorption. This is one of the most common patterns UK GPs see. |
| Low Hb + high MCV | B12 or folate deficiency anaemia. Ask about diet, gut absorption, medications (especially metformin, PPIs), and vegan/vegetarian eating. |
| Low Hb + normal MCV | “Anaemia of chronic disease.” Can occur with chronic inflammation, kidney disease, or long-standing illness. Investigate underlying cause. |
| High WBC + high neutrophils | Bacterial infection or acute inflammation. Ask about symptoms: sore throat, urinary symptoms, chest infection. |
| High WBC + high lymphocytes | Often viral infection. |
| Low platelets | Can be temporary after a viral illness. Persistent low platelets need a GP referral. |
| High platelets | Often a reaction to inflammation, iron deficiency, or infection. If persistent, worth a GP conversation. |
Every Swift Blood Tests health MOT, Men’s Health MOT, Women’s Health MOT, and the Ultimate Men’s and Ultimate Women’s variants, includes a Full Blood Count as one of the core panels. If you’re building an annual baseline of your health, an FBC alongside kidney, liver, cholesterol, thyroid and vitamin markers gives your GP the fullest picture in a single sitting.
No. FBC results are not affected by whether you’ve eaten. You can eat and drink normally. This makes an FBC one of the easiest blood tests to book, walk in the morning, on your lunch break, or at the end of the day.
An FBC measures the concentration and characteristics of red blood cells, white blood cells, and platelets in your blood. It’s used to detect anaemia, infection, inflammation, some blood disorders, and to check overall health.
A private FBC costs about £40 to £65 in the UK depending on provider. Swift Blood Tests offers an FBC at £55, home visit included across Essex, Bromley and Surrey.
No. FBC results are not affected by food. You can eat and drink normally beforehand.
Results come back in 24 to 48 hours from most UK private providers, including Swift Blood Tests. NHS FBC results usually come back in 1 to 3 working days.
An FBC can pick up patterns that suggest some blood cancers (like leukaemia) or that suggest further investigation is needed. It is not a cancer-screening test in the general sense, a normal FBC doesn’t rule out most cancers. See Cancer Research UK on blood tests.
Common causes include recent viral infection, some medications (chemotherapy, some antibiotics, some immune-suppressing drugs), autoimmune conditions, and, less commonly, bone marrow problems. Persistently low white cells need a GP review.
Higher-than-range haemoglobin can occur with dehydration, smoking, chronic lung disease, and (rarely) a condition called polycythaemia. Repeat testing when well-hydrated usually clarifies.
Yes. FBC (Full Blood Count) is the UK term. CBC (Complete Blood Count) is the US term. Same test.
Yes. Swift Blood Tests offers a nurse-led home visit FBC across Essex, Bromley and Surrey. The sample is drawn from your arm and couriered to a UKAS-accredited laboratory the same day. Results come back within 24 to 48 hours.
Book a Full Blood Count with Swift Blood Tests for £55, or add it to a broader Men’s or Women’s Health MOT. Home visits across Essex, Bromley and Surrey are included in the price. Not sure which test is right? Call 01277 652067.
