The full blood count (FBC) — sometimes called a complete blood count — is the most commonly performed blood test in UK clinical practice. It provides a snapshot of the blood's three main cell types (red cells, white cells, and platelets), offering information about anaemia, infection, inflammation, bleeding disorders, bone marrow function, and much more. Understanding what each component measures helps you interpret your results meaningfully.
Red Blood Cell Indices: Haemoglobin, MCV and More
Haemoglobin (Hb) measures the protein in red blood cells that carries oxygen. Normal ranges are approximately 130–170 g/L in men and 120–160 g/L in women. Anaemia is defined as haemoglobin below these thresholds and has many causes including iron deficiency (the most common), B12 and folate deficiency, chronic disease, and haemolysis.
MCV (mean corpuscular volume) measures the average size of red blood cells. Low MCV (microcytic anaemia) is typically caused by iron deficiency or thalassaemia trait. High MCV (macrocytic anaemia) is caused by B12 or folate deficiency, liver disease, hypothyroidism, or certain medications. Normal MCV with low haemoglobin (normocytic anaemia) suggests anaemia of chronic disease, acute blood loss, or haemolysis.
Reticulocytes are immature red blood cells. A raised reticulocyte count suggests the bone marrow is working hard to replace red cells — seen in haemolysis or recent blood loss. A low reticulocyte count in the context of anaemia suggests the bone marrow is not producing enough cells, pointing towards nutritional deficiency or bone marrow disease.
White Blood Cell Count and Differential
The white blood cell (WBC) count measures total immune cells. Normal range is approximately 4–11 × 10⁹/L. An elevated WBC (leukocytosis) is most commonly caused by infection — bacterial infections typically raise neutrophils, while viral infections often raise lymphocytes. Severe leukocytosis may suggest a haematological malignancy such as leukaemia.
The differential WBC count breaks down the total into its component types. Neutrophils are the primary responders to bacterial infection. Lymphocytes are involved in viral immunity and B and T cell function. Eosinophils are elevated in allergic conditions and parasitic infections. Basophils and monocytes play specific roles in immune surveillance and tissue repair.
A low WBC (leucopenia) reduces the ability to fight infection and is seen with viral infections, autoimmune conditions, medication effects (particularly chemotherapy and some immunosuppressants), and bone marrow disease. Neutropenia (specifically low neutrophils) increases infection risk significantly below certain thresholds.
Platelets and Clotting
Platelet count measures the small cells responsible for blood clotting. Normal range is approximately 150–400 × 10⁹/L. Thrombocytopenia (low platelets) below 50 increases risk of spontaneous bleeding; causes include immune thrombocytopenic purpura (ITP), bone marrow disease, hypersplenism, and medication effects. Mild thrombocytopenia is common, often benign, and requires monitoring rather than immediate treatment.
Thrombocytosis (high platelets) is most commonly reactive — occurring in response to infection, inflammation, iron deficiency, or after splenectomy. Primary thrombocytosis due to a myeloproliferative disorder (essential thrombocythaemia) is less common but increases clotting risk and requires haematological assessment.
Platelet distribution width (PDW) and mean platelet volume (MPV) provide additional information about platelet morphology. Large platelets are seen in conditions of high platelet turnover; small platelets in some inherited platelet disorders.
Getting a Full Blood Count Privately in Birmingham
A full blood count at The Vesey, Sutton Coldfield, is processed by an accredited UK laboratory with results available within 24 hours. No GP referral is required, and the test can be requested directly as an individual test or as part of a comprehensive health screening package.
The clinical value of an FBC depends on interpreting results in context. A slightly low haemoglobin in a pregnant woman means something different to the same level in a 65-year-old man with weight loss. Our GP team reviews all results and provides a clinical summary, flagging any results that warrant follow-up investigation or treatment.
An FBC forms part of all The Vesey's health assessment packages and is included in the standard workup for patients presenting with fatigue, breathlessness, recurrent infections, unexplained bruising, or weight loss. Individual FBC testing starts from £32.
Book a GP Appointment — from £90
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Frequently Asked Questions
What does a full blood count test for?
A full blood count measures red blood cells (including haemoglobin and MCV), white blood cells (including the differential count of neutrophils, lymphocytes, and others), and platelets. It screens for anaemia, infection, inflammation, clotting disorders, and bone marrow conditions.
Do I need to fast for a full blood count?
Fasting is not required for a full blood count. However, if your FBC is being tested alongside fasting markers (glucose, lipids), you should fast for 8–12 hours.
What does a low white blood cell count mean?
A low WBC (leucopenia) may indicate a viral infection, autoimmune condition, medication effect, or bone marrow disease. Clinical context and a full blood count differential are needed to interpret a low WBC result.
How much does a private full blood count cost in Birmingham?
A private FBC at The Vesey starts from £32. It is included in all health assessment packages.
The full blood count is the foundation of blood test interpretation in clinical medicine. At The Vesey in Birmingham, FBC testing with clinician review is available within 24 hours from £32. No referral needed. Call 0121 387 3727 or book online.