How to Read Full Blood Count (FBC) Results

A guide for clinic staff: what each line on an FBC report means, approximate adult ranges, the patterns that matter most, and when the analyser’s flags mean a blood film comes before the numbers.

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Also called FBC results, CBC results explained, Full blood count normal range

Published: 17 October 2026

Last updated: 16 October 2026

Before you read the numbers

Reference ranges differ between laboratories, analysers, age groups and sexes, and in pregnancy. The ranges below are approximate adult figures for orientation only — always use the range printed on your report. Children have their own ranges, and the FBC is interpreted by a doctor together with the patient’s symptoms and examination.

Check the patient’s name and the date and time the sample was taken.
Read the analyser’s flags before the numbers.
Compare with the patient’s previous FBC — a trend means more than a single value.
Pass critical results, such as a very low haemoglobin or platelet count, to the doctor at once, following your clinic’s policy.

Red cells: Hb, RBC, HCT and the red-cell indices

Approximate adult ranges; your laboratory sets its own.
Parameter	Approximate adult range	If low	If high
Haemoglobin (Hb, HGB)	Men 13–17 g/dL; women 12–15 g/dL	Anaemia — for example iron deficiency, blood loss, thalassaemia or chronic disease	Dehydration, smoking, chronic lung disease or polycythaemia
RBC (red-cell count)	Men 4.5–5.5 × 10¹²/L; women 3.8–4.8 × 10¹²/L	Anaemia	Dehydration; a high RBC with a low MCV is a common pattern in thalassaemia trait
HCT (haematocrit)	Men 0.40–0.50; women 0.36–0.46	Anaemia	Dehydration; in dengue, a rising HCT with falling platelets is a warning sign
MCV (red-cell size)	80–100 fL	Iron deficiency or thalassaemia	Vitamin B12 or folate deficiency, alcohol, liver disease or some medicines
MCH (haemoglobin per cell)	27–32 pg	Below 27 pg is the thalassaemia screening cut-off in Malaysia; also iron deficiency	Usually follows a high MCV
MCHC	31.5–34.5 g/dL	Pale cells (hypochromia), as in iron deficiency	Spherocytosis, or a sample problem such as cold agglutinins, lipaemia or haemolysis — check the sample first
RDW	About 11.5–14.5%, depending on the analyser	Rarely meaningful	Red cells of mixed sizes — for example iron deficiency, mixed causes or after transfusion

White cells and the differential

A 3-part analyser reports three groups — lymphocytes, mid-sized cells and granulocytes — while a 5-part analyser reports five cell types. Read the absolute counts (× 10⁹/L), not only the percentages: percentages mislead when the total white count is high or low.

Parameter	Approximate adult range (× 10⁹/L)	Common causes of a rise	Common causes of a fall
WBC (total)	4.0–10.0	Bacterial infection, inflammation, steroids or physical stress; rarely leukaemia	Viral infections including dengue, some medicines or marrow problems
Neutrophils	2.0–7.0	Bacterial infection, inflammation or steroids	Viral infection or some medicines; some healthy people run lower counts
Lymphocytes	1.0–3.0	Viral infection; persistent lymphocytosis in an adult needs review	Steroids, acute stress or some infections
Monocytes	0.2–1.0	Chronic infection or recovery	Rarely meaningful alone
Eosinophils	0.02–0.5	Allergy, asthma, eczema or worm infection	Steroids
Basophils	0.02–0.1	Uncommon; if persistent, a doctor should review it	Not meaningful

Platelets and MPV

PLT (platelet count)

About 150–400 × 10⁹/L in adults, up to 450 in some laboratories. A low count is common in dengue and other viral infections and can also follow medicines or immune disease. A high count can follow infection, inflammation, bleeding or iron deficiency.

A falsely low count

Platelets can clump in the EDTA tube or in a partly clotted sample and be counted low while the patient’s real count is normal. If the result does not fit the patient, check the flags, the histogram and a film, or recollect.

Citrate counts for clumping samples

MPV

Mean platelet volume — average platelet size. Larger platelets can appear when the marrow is producing them quickly, but MPV is hard to interpret alone and its range differs between analysers.

Common patterns

Pattern	Often suggests	Usual next step
Low Hb with low MCV and MCH	Iron deficiency or thalassaemia trait	Ferritin; MCH below 27 pg prompts thalassaemia screening
Low Hb with high MCV	Vitamin B12 or folate deficiency, alcohol, liver disease, hypothyroidism or some medicines	B12, folate and a film
Low Hb with normal indices	Recent blood loss, chronic disease, kidney disease or an early deficiency	Reticulocyte count and clinical review
High WBC with neutrophilia	Bacterial infection, inflammation or steroids	Clinical assessment; a film if flagged
Low WBC and platelets with a rising HCT in a febrile patient	Dengue, especially during an outbreak	Manage and follow up under the Malaysian dengue guidelines
Isolated low platelets	Viral infection, medicines or immune thrombocytopenia — or clumping in the tube	Film and, if clumped, a recollection
Two or three cell lines low	A marrow problem, severe infection or B12 deficiency	Prompt medical review and a film

Flags and when a film comes first

A flag is the analyser’s warning that a sample may contain abnormal cells or interference. A flagged result should not be released without review.

Flags for blasts, atypical lymphocytes, immature granulocytes or nucleated red cells.
Suspected platelet clumps, or a very low platelet count.
An unusual histogram, such as a double peak.
A very high MCHC or an implausible result — check for a sample problem first.
Results that do not fit the patient’s condition.
If no one at the clinic can read a blood film, agree a referral route with an outside laboratory.

Hematology Analyser supply near you

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Frequently asked questions

What is a normal haemoglobin level for an adult?

Roughly 13–17 g/dL for men and 12–15 g/dL for women. The exact range depends on the laboratory and analyser and differs for children and in pregnancy, so use the range printed on the report.

What do a low MCV and MCH mean?

Small, pale red cells. In Malaysia the two commonest causes are iron deficiency and thalassaemia trait. An MCH below 27 pg is the thalassaemia screening cut-off, and doctors usually check iron stores as well.

What can cause a low platelet count on an FBC?

Dengue and other viral infections, medicines and immune disease are common causes. Platelets clumping in the tube can also give a falsely low count, so an unexpected result is checked with a film or a new sample.

Should I read the percentages or the absolute counts in the differential?

The absolute counts. Percentages depend on the total white count, so a normal-looking percentage can hide a low or high number of a cell type.

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